ASCP MLS Hematology

Which of the following is contained in the primary granules of the neutrophil? A. Lactoferrin B. Myeloperoxidase C. Histamine D. Alkaline phosphatase

B. Myeloperoxidase, lysozyme, and acid phosphatase are enzymes that are contained in the primary granules of neutrophils. The contents of secondary and tertiary granules include lactoferrin, collagenase, NADPH oxidase, and alkaline phosphatase.

Sodium fluoride may be added to the naphthyl ASD acetate (NASDA) esterase reaction. The fluoride is added to inhibit a positive reaction with: A. Megakaryocytes B. Monocytes C. Erythrocytes D. Granulocytes

B. NASDA stains monocytes (and monoblasts) and granulocytes (and myeloblasts). The addition of fluoride renders the monocytic cells (and blasts) negative, thus allowing for differentiation from the granulocytic cells, which remain positive.

The basic pathophysiological mechanisms responsible for producing signs and symptoms in leukemia include all of the following except: A. Replacement of normal marrow precursors by leukemic cells causing anemia B. Decrease in functional leukocytes causing infection C. Hemorrhage secondary to thrombocytopenia D. Decreased erythropoietin production

D. A normal physiological response to anemia would be an increase in the kidney's production of erythropoietin. The accumulation of leukemic cells in the bone marrow leads to marrow failure, which is manifested by anemia, thrombocytopenia, and granulocytopenia.

The Coulter principle for counting of cells is based upon the fact that: A. Isotonic solutions conduct electricity better than cells do B. Conductivity varies proportionally to the number of cells C. Cells conduct electricity better than saline does D. Isotonic solutions cannot conduct electricity

A Electronic cell (Coulter) counters use the principle of electrical impedance. Two electrodes suspended in isotonic solutions are separated by a glass tube having a small aperture. A vacuum is applied, and as a cell passes through the aperture it impedes the flow of current and generates a voltage pulse.

An M:E ratio of 10:1 is most often seen in: A. Thalassemia B. Leukemia C. Polycythemia vera D. Myelofibrosis

B. A disproportionate increase in the myeloid component of the bone marrow is usually the result of a leukemic state. The normal M:E ratio is approximately 4:1 in adults with normal cellularity.

Variation in red cell size observed on the peripheral smear is described as: A. Anisocytosis B. Hypochromia C. Poikilocytosis D. Pleocytosis

A. A mature erythrocyte is approximately 7-8 μm in diameter. Variation in normal size is denoted by the term anisocytosis. Hypochromia is a term that indicates increased central pallor in erythrocytes, and poikilocytosis denotes variation in red cell shape.

SITUATION: A peripheral smear shows 75% blasts. These stain positive for both Sudan Black B (SBB) and peroxidase. Given these values, which of the following disorders is most likely? A. Acute myelocytic leukemia (AML) B. CML C. Acute undifferentiated leukemia (AUL) D. Acute lymphocytic leukemia (ALL)

A. AML blasts stain positive for Sudan Black B and peroxidase. Usually, fewer than 10% blasts are found in the peripheral smear of patients with CML, unless there has been a transition to blast crisis. The organelles in the cells of AUL are not mature enough to stain positive for SBB or peroxidase. Blasts in ALL are characteristically negative with these stains.

What would be the most likely designation by the WHO for the FAB AML M3 by the French-American-British classification? A. AML with t(15;17) B. AML with mixed lineage C. AML with t(8;21) D. AML with inv(16)

A. AML with t(15;17) is classified under the category of AML with Recurrent Genetic Abnormalities by the WHO. Acute promyelocytic leukemia (PML; known as M3 under the FAB system) is composed of abnormal promyelocytes with heavy granulation, sometimes obscuring the nucleus, and abundant cytoplasm. Acute promyelocytic leukemia (APL) contains a translocation that results in the fusion of a transcription factor called PML on chromosome 15 with the alpha (α)-retinoic acid receptor gene (RARα) on chromosome 17.

Which condition will shift the oxyhemoglobin dissociation curve to the right? A. Acidosis B. Alkalosis C. Multiple blood transfusions D. Increased quantities of hemoglobin S or C

A. Acidosis is associated with a shift to the right of the oxyhemoglobin dissociation curve and, therefore, increased oxygen release (decreased affinity of Hgb for oxygen). Alkalosis does the opposite. Multiple blood transfusions shift the curve to the left because the transfused blood is low in 2,3-DPG. Hgb S and Hgb C do not change the affinity of oxygen for hemoglobin; however, many hemoglobinopathies do. For example, Hgb Kansas causes a right shift and Hgb Chesapeake causes a left shift of the oxyhemoglobin dissociation curve.

In which age group does acute lymphoblastic leukemia occur with the highest frequency? A. 1-15 years B. 20-35 years C. 45-60 years D. 60-75 years

A. Acute lymphoblastic leukemia (ALL) usually affects children from ages 1-15 and is the most common type of acute leukemia in this age group. In addition, ALL constitutes the single most prevalent malignancy in pediatric patients.

Which of the following is a characteristic of Auer rods? A. They are composed of azurophilic granules B. They stain periodic acid-Schiff (PAS) positive C. They are predominantly seen in chronic myelogenous leukemia (CML) D. They are nonspecific esterase positive

A. Auer rods are a linear projection of primary azurophilic granules, and are present in the cytoplasm of myeloblasts and monoblasts in patients with acute leukemia.

CML is distinguished from leukemoid reaction by which of the following? A. CML: low LAP; leukemoid: high LAP B. CML: high LAP; leukemoid: low LAP C. CML: high WBC; leukemoid: normal WBC D. CML: high WBC; leukemoid: higher WBC

A. CML causes a low LAP score, whereas an elevated or normal score occurs in a leukemoid reaction. CML cannot be distinguished by WBC count because both CML and leukemoid reaction have a high count.

Which inclusions may be seen in leukocytes? A. Döhle bodies B. Basophilic stippling C. Malarial parasites D. Howell-Jolly bodies

A. Döhle bodies are RNA-rich areas within polymorphonuclear neutrophils (PMNs) that are oval and light blue in color. Although often associated with infectious states, they are seen in a wide range of conditions and toxic reactions, including hemolytic and pernicious anemias, chronic granulocytic leukemia, and therapy with antineoplastic drugs. The other inclusions are associated with erythrocytes.

All of the following factors may influence the erythrocyte sedimentation rate (ESR) except: A. Blood drawn into a sodium citrate tube B. Anisocytosis, poikilocytosis C. Plasma proteins D. Caliber of the tube

A. EDTA and sodium citrate can be used without any effect on the ESR. Anisocytosis and poikilocytosis may impede rouleaux formation, thus causing a low ESR. Plasma proteins, especially fibrinogen and immunoglobulins, enhance rouleaux, increasing the ESR. Reference ranges must be established for different caliber tubes.

In essential thrombocythemia, the platelets are: A. Increased in number and functionally abnormal B. Normal in number and functionally abnormal C. Decreased in number and functional D. Decreased in number and functionally abnormal

A. In essential thrombocythemia, the platelet count is extremely elevated. These platelets are abnormal in function, leading to both bleeding and thrombotic diathesis.

Insufficient centrifugation will result in: A. A false increase in hematocrit (Hct) value B. A false decrease in Hct value C. No effect on Hct value D. All of these options, depending on the patient

A. Insufficient centrifugation does not pack down the red blood cells; therefore, the Hct, which is the volume of packed cells, will increase.

Iron deficiency anemia is characterized by: A. Decreased plasma iron, decreased % saturation, increased total iron-binding capacity (TIBC) B. Decreased plasma iron, decreased plasma ferritin, normal RBC porphyrin C. Decreased plasma iron, decreased % saturation, decreased TIBC D. Decreased plasma iron, increased % saturation, decreased TIBC

A. Iron deficiency anemia is characterized by decreased plasma iron, increased TIBC, decreased % saturation, and microcytic, hypochromic anemia. Iron deficiency occurs in three phases: iron depletion, iron-deficient erythropoiesis, and iron deficiency anemia.

All of the following are associated with intravascular hemolysis except: A. Methemoglobinemia B. Hemoglobinuria C. Hemoglobinemia D. Decreased haptoglobin

A. Methemoglobin occurs when iron is oxidized to the ferric state. Normally, iron is predominantly in the ferrous state in the hemoglobin that circulates. During intravascular hemolysis, the red cells rupture, releasing hemoglobin directly into the bloodstream. Haptoglobin is a protein that binds to free Hgb. The increased free Hgb in intravascular hemolysis causes depletion of haptoglobin. As haptoglobin is depleted, unbound hemoglobin dimers appear in the plasma (hemoglobinemia) and are filtered through the kidneys and reabsorbed by the renal tubular cells. The renal tubular uptake capacity is approximately 5 g per day of filtered hemoglobin. Beyond this level, free hemoglobin appears in the urine (hemoglobinuria). Hemoglobinuria is associated with hemoglobinemia.

Neutropenia is present in patients with which absolute neutrophil counts? A. <1.5 × 10^9/L B. <5.0 × 10^9/L C. <10.0 × 10^9/L D. <15.0 × 10^9/L

A. Neutropenia is defined as an absolute decrease in the number of circulating neutrophils. This condition is present in patients having neutrophil counts of less than 1.5 × 109/L.

A decreased osmotic fragility test would be associated with which of the following conditions? A. Sickle cell anemia B. Hereditary spherocytosis C. Hemolytic disease of the newborn D. Acquired hemolytic anemia

A. Osmotic fragility is decreased when numerous sickle cells and target cells are present and is increased in the presence of spherocytes. Spherocytes are a prominent feature of hereditary spherocytosis (HS), hemolytic disease of the newborn, and acquired hemolytic anemia. The osmotic fragility test is increased in the presence of spherocytes, whereas this test is decreased when sickle cells, target cells, and other poikilocytes are present.

Which of the following reactions are often positive in ALL but are negative in AML? A. Terminal deoxynucleotidyl transferase and PAS B. Chloroacetate esterase and nonspecific esterase C. Sudan Black B and peroxidase D. New methylene blue and acid phosphatase

A. PAS is positive in about 50% of ALL with L1 and L2 morphology but is negative in ALL with L3 morphology (B-cell ALL). Terminal deoxynucleotidyl transferase is positive in all types of ALL except L3. Both terminal deoxynucleotidyl transferase and PAS are negative in AML.

Which of the following is most true of paroxysmal nocturnal hemoglobinuria (PNH)? A. It is a rare acquired stem cell disorder that results in hemolysis B. It is inherited as a sex-linked trait C. It is inherited as an autosomal dominant trait D. It is inherited as an autosomal recessive trait

A. PNH is a rare acquired stem cell disorder that results in abnormalities of the red cell membrane. This causes the red cells to be highly sensitive to complement-mediated hemolysis. Because this is a stem cell disorder, abnormalities are seen in leukocytes and platelets, as well as in red cells. PNH is characterized by recurrent, episodic intravascular hemolysis, hemoglobinuria, and venous thrombosis.

Sickle cell disorders are: A. Hereditary, intracorpuscular RBC defects B. Hereditary, extracorpuscular RBC defects C. Acquired, intracorpuscular RBC defects D. Acquired, extracorpuscular RBC defects

A. Sickle cell disorders are intracorpuscular red cell defects that are hereditary and result in defective Hgbs being produced. The gene for sickle cell can be inherited either homozygously or heterozygously.

Features of secondary polycythemia include all of the following except: A. Splenomegaly B. Decreased oxygen saturation C. Increased red cell mass D. Increased erythropoietin

A. Splenomegaly is a feature of PV but not characteristic of secondary polycythemia. The red cell mass is increased in both primary polycythemia (PV) and secondary polycythemia. Erythropoietin is increased and oxygen saturation is decreased in secondary polycythemia.

Neutrophil phagocytosis and particle ingestion are associated with an increase in oxygen utilization called respiratory burst. What are the two most important products of this biochemical reaction? A. Hydrogen peroxide and superoxide anion B. Lactoferrin and NADPH oxidase C. Cytochrome b and collagenase D. Alkaline phosphatase and ascorbic acid

A. The biochemical products of the respiratory burst that are involved with neutrophil particle ingestion during phagocytosis are hydrogen peroxide and superoxide anion. The activated neutrophil discharges the enzyme NADPH oxidase into the phagolysosome, where it converts O2 to superoxide anion (O2-), which is then reduced to hydrogen peroxide (H2O2).

A manual white blood cell (WBC) count was performed. A total of 36 cells were counted in all 9-mm^2 squares of a Neubauer-ruled hemacytometer. A 1:10 dilution was used. What is the WBC count? A. 0.4 × 10^9/L B. 2.5 × 10^9/L C. 4.0 × 10^9/L D. 8.0 × 10^9/L

A. The formula used for calculating manual cell counts using a hemacytometer is: Number of cells counted × dilution factor × depth factor (10) divided by the area. In this example, 36 × 10 × 10 = 3600 ÷ 9 = 400/mm^3 or 0.4 × 10^9/L.

Which of the following is the preferable site for bone marrow aspiration and biopsy in an adult? A. Iliac crest B. Sternum C. Tibia D. Spinous processes of a vertebra

A. The iliac crest is the most frequently used site for bone marrow aspiration and biopsy. This site is the safest and most easily accessible, with the bone just beneath the skin, and neither blood vessels nor nerves are in the vicinity.

A 25-year-old woman saw her physician with symptoms of jaundice, acute cholecystitis, and an enlarged spleen. On investigation, numerous gallstones were discovered. Review the following CBC results: WBCs = 11.1 × 10^9/L RBCs = 3.33 × 10^12/L Hgb = 11.5 g/dL Hct = 31.6 mL/dL MCV = 100 fL MCH = 34.5 pg MCHC = 37.5% PLT = 448 × 10^9/L WBC differential: 13 band neutrophils; 65 segmented neutrophils; 15 lymphocytes; 6 monocytes; 1 eosinophil RBC morphology: 3+ spherocytes, 1+ polychromasia What follow-up laboratory test would provide valuable information for this patient? A. Osmotic fragility B. Hgb electrophoresis C. G6PD assay D. Methemoglobin reduction test

A. The osmotic fragility test is indicated as a confirmatory test for the presence of numerous spherocytes, and individuals with hereditary spherocytosis (HS) have an increased osmotic fragility. The MCHC is elevated in more than 50% of patients with spherocytosis, and this parameter can be used as a clue to the presence of HS. Spherocytes have a decreased surface-to-volume ratio, probably resulting from mild cellular dehydration.

What effect would using a buffer at pH 6.0 have on a Wright's-stained smear? A. Red cells would be stained too pink B. White cell cytoplasm would be stained too blue C. Red cells would be stained too blue D. Red cells would lyse on the slide

A. The pH of the buffer is critical in Romanowsky stains. When the pH is too low (<6.4), the red cells take up more acid dye (eosin), becoming too pink. Leukocytes also show poor nuclear detail when the pH is decreased.

Congenital dyserythropoietic anemias (CDAs) are characterized by: A. Bizarre multinucleated erythroblasts B. Cytogenetic disorders C. Megaloblastic erythropoiesis D. An elevated M:E ratio

A. There are four classifications of CDAs, each characterized by ineffective erythropoiesis, increased unconjugated bilirubin, and bizarre multinucleated erythroid precursors.

In which age group would 60% lymphocytes be a normal finding? A. 6 months-2 years B. 4-6 years C. 11-15 years D. 40-60 years

A. There is a relative neutropenia in children from ages 4 months to 4 years. Because of this, the percentage of lymphocytes is increased in this population. This is commonly referred to as a reversal in the normal differential percentage (or inverted differential).

What term describes the change in shape of erythrocytes seen on a Wright's-stained peripheral blood smear? A. Poikilocytosis B. Anisocytosis C. Hypochromia D. Polychromasia

A. Variation in shape of the erythrocytes on a peripheral blood smear is poikilocytosis. Anisocytosis refers to a change in size. Hypochromia is an increase in central pallor in erythrocytes. Polychromasia describes the bluish tinge of the immature erythrocytes (reticulocytes) circulating in the peripheral blood.

Waldenström's macroglobulinemia is a malignancy of the: A. Lymphoplasmacytoid cells B. Adrenal cortex C. Myeloblastic cell lines D. Erythroid cell precursors

A. Waldenström's macroglobulinemia is a malignancy of the lymphoplasmacytoid cells, which manufacture IgM. Although the cells secrete immunoglobulin, they are not fully differentiated into plasma cells and lack the characteristic perinuclear halo, deep basophilia, and eccentric nucleus characteristic of classic plasma cells.

A patient with a vitamin B12 anemia is given a high dosage of folate. Which of the following is expected as a result of this treatment? A. An improvement in neurological problems B. An improvement in hematological abnormalities C. No expected improvement D. Toxicity of the liver and kidneys

B. Administration of folic acid to a patient with vitamin B12 deficiency will improve the hematological abnormalities; however, the neurological problems will continue. This helps to confirm the correct diagnosis of vitamin B12 deficiency.

What red cell inclusion may be seen in the peripheral blood smear of a patient postsplenectomy? A. Toxic granulation B. Howell-Jolly bodies C. Malarial parasites D. Siderotic granules

B. As a result of splenectomy, Howell-Jolly bodies may be seen in great numbers. One of the main functions of the spleen is the pitting function, which allows inclusions to be removed from the red cell without destroying the cell membrane.

Auer rods may be seen in all of the following except: A. Acute myelomonocytic leukemia (M4) B. Acute lymphoblastic leukemia C. Acute myeloid leukemia without maturation (M1) D. Acute promyelocytic leukemia (M3)

B. Auer rods are not seen characteristically in lymphoblasts. They may be seen in myeloblasts, promyelocytes, and monoblasts.

Review the following CBC results on a 70-year-old man: WBCs = 58.2 × 10^9/L RBCs = 2.68 × 10^12/L Hgb = 8.5 g/dL Hct = 26.5 mL/dL% MCV = 98 fL MCH = 31.7 pg MCHC = 32.6% PLT = 132 × 10^9/L Differential: 96 lymphocytes; 2 band neutrophils; 2 segmented neutrophils; 25 smudge cells/100 WBCs What is the most likely diagnosis based on these values? A. Acute lymphocytic leukemia B. Chronic lymphocytic leukemia (CLL) C. Infectious mononucleosis D. Myelodysplastic syndrome

B. CLL is a disease of the elderly, classically associated with an elevated WBC count and relative and absolute lymphocytosis. CLL is twice as common in men, and smudge cells (WBCs with little or no surrounding cytoplasm) are usually present in the peripheral blood smear. CLL may occur with or without anemia or thrombocytopenia. The patient's age and lack of blasts rule out acute lymphocytic leukemia. Similarly, the patient's age and the lack of atypical lymphocytes make infectious mononucleosis unlikely. Myelodysplastic syndromes may involve the erythroid, granulocytic, or megakaryocytic cell lines but not the lymphoid cells.

The morphological characteristic(s) associated with the Chédiak-Higashi syndrome is (are): A. Pale blue cytoplasmic inclusions B. Giant lysosomal granules C. Small, dark-staining granules and condensed nuclei D. Nuclear hyposegmentation

B. Chédiak-Higashi syndrome is a disorder of neutrophil phagocytic dysfunction caused by depressed chemotaxis and delayed degranulation. The degranulation disturbance is attributed to interference from the giant lysosomal granules characteristic of this disorder.

Which of the following electrophoretic results is consistent with a diagnosis of sickle cell trait? A. Hgb A: 40% Hgb S: 35% Hgb F: 5% B. Hgb A: 60% Hgb S: 40% Hgb A2: 2% C. Hgb A: 0% Hgb A2: 5% Hgb F: 95% D. Hgb A: 80% Hgb S: 10% Hgb A2: 10%

B. Electrophoresis at alkaline pH usually shows 50%- 70% Hgb A, 20%-40% Hgb S, and normal levels of Hgb A2 in a patient with the sickle cell trait.

Which of the following erythrocyte inclusions can be visualized with supravital stain but cannot be detected on a Wright's-stained blood smear? A. Basophilic stippling B. Heinz bodies C. Howell-Jolly bodies D. Siderotic granules

B. Heinz bodies are irregular, refractile, purple inclusions that are not visible with Wright's stain but show up with supravital staining. The other three inclusions can be detected with Wright's stain.

In addition to morphology, cytochemistry, and immunophenotyping, the WHO classification of myelo- and lymphoproliferative disorders is based upon which characteristic? A. Proteomics B. Cytogenetic abnormalities C. Carbohydrate-associated tumor antigen production D. Cell signaling and adhesion markers

B. In addition to morphology, cytochemical stains, and flow cytometry, the WHO classification relies heavily on chromosomal and molecular abnormalities.

If a patient has a reticulocyte count of 7% and an Hct of 20%, what is the corrected reticulocyte count? A. 1.4% B. 3.1% C. 3.5% D. 14%

B. In anemic states, the reticulocyte percentage is not a true measure of reticulocyte production. The following formula must be applied to calculate the corrected (for anemia) reticulocyte count. Corrected reticulocyte count = reticulocytes (%) × Hct ÷ 45, the average normal Hct. In this case, 7 × (20 ÷ 45) = 3.1.

Which anemia has red cell morphology similar to that seen in iron deficiency anemia? A. Sickle cell anemia B. Thalassemia syndrome C. Pernicious anemia D. Hereditary spherocytosis

B. Iron deficiency anemia and thalassemia are both classified as microcytic, hypochromic anemias. Iron deficiency anemia is caused by defective heme synthesis; whereas thalassemia is caused by decreased globin chain synthesis.

What is the major type of leukocyte seen in the peripheral smear of a patient with aplastic anemia? A. Segmented neutrophil B. Lymphocyte C. Monocyte D. Eosinophil

B. Lymphocytes constitute the majority of the nucleated cells seen. The bone marrow in aplastic anemia is spotty with patches of normal cellularity. Absolute granulocytopenia is usually present; however, lymphocyte production is less affected.

Mean cell volume (MCV) is calculated using the following formula: A. (Hgb / RBC) × 10 B. (Hct / RBC) × 10 C. (Hct / Hgb) × 100 D. (Hgb / RBC) × 100

B. MCV is the average "volume" of the red cells. This is obtained by dividing the Hct or packed cell volume (PCV) by the red blood cell (RBC) count in millions per microliter of blood and multiplying by 10. The MCV is expressed in cubic microns (μm3) or femtoliters (fL).

All of the following are characteristics of megaloblastic anemia except: A. Pancytopenia B. Elevated reticulocyte count C. Hypersegmented neutrophils D. Macrocytic erythrocyte indices

B. Megaloblastic anemias are associated with an ineffective erythropoiesis and therefore a decrease in the reticulocyte count.

Qualitative and quantitative neutrophil changes noted in response to infection include all of the following except: A. Neutrophilia B. Pelgeroid hyposegmentation C. Toxic granulation D. Vacuolization

B. Neutrophil changes associated with infection may include neutrophilia, shift to the left, toxic granulation, Döhle bodies, and vacuolization. Pelgeroid hyposegmentation is noted in neutrophils from individuals with the congenital Pelger-Huët anomaly and as an acquired anomaly induced by drug ingestion or secondary to conditions such as leukemia.

What influence does the Philadelphia (Ph1) chromosome have on the prognosis of patients with chronic myelocytic leukemia? A. It is not predictive B. The prognosis is better if Ph1 is present C. The prognosis is worse if Ph1 is present D. The disease usually transforms into AML when Ph1 is present

B. Ninety percent of patients with CML have the Philadelphia chromosome. This appears as a long arm deletion of chromosome 22, but is actually a translocation between the long arms of chromosomes 22 and 9. The ABL oncogene from chromosome 9 forms a hybrid gene with the bcr region of chromosome 22. This results in production of a chimeric protein with tyrosine kinase activity that activates the cell cycle. The prognosis for CML is better if the Philadelphia chromosome is present. Often, a second chromosomal abnormality occurs in CML before blast crisis.

In PV, what is characteristically seen in the peripheral blood? A. Panmyelosis B. Pancytosis C. Pancytopenia D. Panhyperplasia

B. PV is a myeloproliferative disorder characterized by uncontrolled proliferation of erythroid precursors. However, production of all cell lines is usually increased. Panhyperplasia is a term used to describe the cellularity of the bone marrow in PV.

Which of the following may be seen in the peripheral blood smear of a patient with obstructive liver disease? A. Schistocytes B. Macrocytes C. Howell-Jolly bodies D. Microcytes

B. Patients with obstructive liver disease may have red blood cells that have an increased tendency toward the deposition of lipid on the surface of the red cell. Consequently, the red cells are larger or more macrocytic than normal red cells.

A 1:200 dilution of a patient's sample was made and 336 red cells were counted in an area of 0.2 mm^2. What is the RBC count? A. 1.68 × 1012/L B. 3.36 × 1012/L C. 4.47 × 1012/L D. 6.66 × 1012/L

B. RBC count = number of cells counted × dilution factor × depth factor (10), divided by the area. In this example, 336 × 200 × 10 = 672,000 ÷ 0.2 = 3.36 × 106/mm^3 = 3.36 × 10^12/L.

The erythrocytosis seen in relative polycythemia occurs because of: A. Decreased arterial oxygen saturation B. Decreased plasma volume of circulating blood C. Increased erythropoietin levels D. Increased erythropoiesis in the bone marrow

B. Relative polycythemia is caused by a reduction of plasma rather than an increase in red blood cell volume or mass. Red cell mass is increased in both PV and secondary polycythemia, but erythropoietin levels are high only in secondary polycythemia.

Autoimmune hemolytic anemia is best characterized by which of the following? A. Increased levels of plasma C3 B. Spherocytic red cells C. Decreased osmotic fragility D. Decreased unconjugated bilirubin

B. Spherocytes are characteristic of autoimmune hemolytic anemia and result in an increased osmotic fragility. In autoimmune hemolytic anemias (AIHAs), production of autoantibodies against one's own red cells causes hemolysis or phagocytic destruction of RBCs. A positive direct antiglobulin (DAT or Coombs') test identifies in vivo antibody-coated and complement-coated red cells. A positive DAT distinguishes AIHA from other types of hemolytic anemia that produce spherocytes.

A falsely elevated Hct is obtained. Which of the following calculated values will not be affected? A. MCV B. MCH C. MCHC D. Red cell distribution width (RDW)

B. The MCH = Hgb × 10/RBC count and is not affected by the Hct. The MCV = Hct × 10/RBC count, and MCHC = Hgb × 100/Hct; therefore, an erroneous Hct will affect these parameters. Centrifugal force for microhematocrit determination should be 12,000 g for 5 min in order to avoid error caused by trapped plasma. The red cell distribution width (RDW) is calculated by electronic cell counters and reflects the variance in the size of the red cell population. Electronic cell counters calculate Hct from the MCV and RBC count. Therefore, the RDW would be affected by an erroneous MCV.

Using an electronic cell counter analyzer, an increased RDW should correlate with: A. Spherocytosis B. Anisocytosis C. Leukocytosis D. Presence of nRBCs

B. The RDW parameter correlates with the degree of anisocytosis seen on the morphological examination. The reference range is 11.5%-14.5%.

The WHO classification requires what percentage for the blast count in the blood or bone marrow for the diagnosis of AML? A. At least 30% B. At least 20% C. At least 10% D. Any percentage

B. The WHO classification of AML requires that ≥20% of nucleated bone marrow cells be blasts, while the FAB classification generally requires ≥30%. WHO classifies AML into five subgroups: These are acute myeloid leukemias with recurrent genetic disorders; acute myeloid leukemia with multilineage dysplasia; acute myeloid leukemia and myelodysplastic syndromes, therapy related; acute myeloid leukemia not otherwise categorized; and acute leukemia of ambiguous lineage.

Disseminated intravascular coagulation (DIC) is most often associated with which of the following types of acute leukemia? A. Acute myeloid leukemia without maturation B. Acute promyelocytic leukemia C. Acute myelomonocytic leukemia D. Acute monocytic leukemia

B. The azurophilic granules in the leukemic promyelocytes in patients with acute promyelocytic leukemia contain thromboplastic substances. These activate soluble coagulation factors, which when released into the blood, cause DIC.

Review the following CBC results: WBCs = 11.0 × 10^9/L RBCs = 3.52 × 10^12/L Hgb = 10.0 g/dL Hct = 29.9 mL/dL 12 NRBCs/100 WBCs MCV = 85.0 fL MCH = 28.4 pg MCHC = 33.4% PLT = 155 × 10^9/L RBC morphology: Moderate polychromasia, 3+ target cells, few schistocytes Which of the following additional laboratory tests would yield informative diagnostic information for this patient? A. Osmotic fragility B. Hgb electrophoresis C. Sugar water test D. Bone marrow examination

B. The findings of a moderate anemia, numerous target cells seen on a peripheral blood smear, as well as the presence of NRBCs, are often associated with hemoglobinopathies. Hemoglobin electrophoresis at alkaline pH is a commonly performed test to correctly diagnose the type of hemoglobinopathy.

A 19-year-old man came to the emergency department with severe joint pain, fatigue, cough, and fever. Review the following laboratory results: WBCs: 21.0 × 10^9/L RBCs: 3.23 × 10^12/L Hgb: 9.6 g/dL PLT: 252 × 10^9/L Differential: 17 band neutrophils; 75 segmented neutrophils; 5 lymphocytes; 2 monocytes; 1 eosinophil; 26 NRBCs What is the corrected WBC count? A. 8.1 × 10^9/L B. 16.7 × 10^9/L C. 21.0 × 10^9/L D. 80.8 × 10^9/L

B. The formula for correcting the WBC count for the presence of NRBCs is: Total WBC × 100 or (21.0 × 100) ÷ 126 = 16.7 × 10^9/L where total WBC = WBCs × 109/L, 100 is the number of WBCs counted in the differential, and 126 is the sum of NRBCs plus WBCs counted in the differential.

A Miller disk is an ocular device used to facilitate counting of: A. Platelets B. Reticulocytes C. Sickle cells D. Nucleated red blood cells (nRBCs)

B. The manual reticulocyte count involves the counting of 1,000 RBCs. The Miller disk is a reticle (grid) that is placed in the eyepiece of the microscope and divides the field into two squares, one being nine times larger in size than the other. Reticulocytes are enumerated in both the squares. Mature red cells are counted in the smaller one.

The osmotic fragility test result in a patient with thalassemia major would most likely be: A. Increased B. Decreased C. Normal D. Decreased after incubation at 37°C

B. The osmotic fragility is decreased because numerous target cells are present and have increased surface volume in thalassemia major patients.

A patient has 80 nucleated red blood cells per 100 leukocytes. In addition to increased polychromasia on the peripheral smear, what other finding may be present on the CBC? A. Increased platelets B. Increased MCV C. Increased Hct D. Increased red blood cell count

B. The patient will have an increased MCV. One of the causes of a macrocytic anemia that is not megaloblastic is an increased reticulocyte count, here noted as increased polychromasia. Reticulocytes are polychromatic macrocytes; therefore, the MCV is slightly increased.

What staining method is used most frequently to stain and manually count reticulocytes? A. Immunofluorescence B. Supravital staining C. Romanowsky staining D. Cytochemical staining

B. The reticulum within the reticulocytes consists of ribonucleic acid (RNA), which cannot be stained with Wright's stain. Supravital staining with new methylene blue is used to identify the reticulocytes.

Which of the following organs is responsible for the "pitting process" for RBCs? A. Liver B. Spleen C. Kidney D. Lymph nodes

B. The spleen is the supreme filter of the body, pitting imperfections from the erythrocyte without destroying the integrity of the membrane.

Select the amino acid substitution that is responsible for sickle cell anemia. A. Lysine is substituted for glutamic acid at the sixth position of the α-chain B. Valine is substituted for glutamic acid at the sixth position of the β-chain C. Valine is substituted for glutamic acid at the sixth position of the α-chain D. Glutamine is substituted for glutamic acid at the sixth position of the β-chain

B. The structural mutation for Hgb S is the substitution of valine for glutamic acid at the sixth position of the β-chain. Because glutamic acid is negatively charged, this decreases its rate of migration toward the anode at pH 8.6.

Which of the following parameters may be similar for the anemia of inflammation and iron deficiency anemia? A. Normocytic indices B. Decreased serum iron concentration C. Ringed sideroblasts D. Pappenheimer bodies

B. Thirty to fifty percent of the individuals with the anemia of chronic inflammation demonstrate a microcytic hypochromic blood picture with decreased serum iron. Serum iron is decreased because it is unable to escape from the RE cells to be delivered to the nucleated red cells in the bone marrow.

Which of the following results on an automated differential suggests that a peripheral smear should be reviewed manually? A. Segs = 70% B. Band = 6% C. Mono = 15% D. Eos = 2%

C. A relative monocyte count of 15% is abnormal, given that the baseline monocyte count in a normal differential is between 1% and 8%. An increased monocyte count may signal a myeloproliferative process such as chronic myelomonocytic leukemia, an inflammatory response, or abnormal lymphocytes that may have been counted as monocytes by an automated cell counter.

Cells that exhibit a positive stain with acid phosphatase and are not inhibited with tartaric acid are characteristically seen in: A. Infectious mononucleosis B. Infectious lymphocytosis C. Hairy cell leukemia D. T-cell acute lymphoblastic leukemia

C. A variable number of malignant cells in hairy cell leukemia (HCL) will stain positive with tartrateresistant acid phosphatase (TRAP+). Although this cytochemical reaction is fairly specific for HCL, TRAP activity has occasionally been reported in B-cell and rarely T-cell leukemia.

What would be the most likely designation by the WHO for the FAB AML M2 by the French-American-British classification? A. AML with t(15;17) B. AML with mixed lineage C. AML with t(8;21) D. AML with inv(16)

C. AML with t(8;21) is classified under the category of AML with Recurrent Genetic Abnormalities by the WHO. This translocation occurs in up to 15% of cases of AML and may be the most common translocation. The AML1-ETO translocation occurs chiefly in younger patients and often in cases of acute myeloblastic leukemia with maturation, FAB M2. The translocation involves the fusion of the AML1 gene on chromosome 21 with the ETO gene on chromosome 8.

Which type of anemia is usually present in a patient with acute leukemia? A. Microcytic, hyperchromic B. Microcytic, hypochromic C. Normocytic, normochromic D. Macrocytic, normochromic

C. Acute leukemia is usually associated with a normocytic normochromic anemia. Anemia in acute leukemia is usually present from the onset and may be severe; however, there is no inherent nutritional deficiency leading to either a microcytic, hypochromic, or megaloblastic process.

What would be the most likely classification by the WHO for the FAB AML M7 by the French-American-British classification? A. Acute myeloid leukemias with recurrent genetic abnormalities B. Acute myeloid leukemia with multilineage dysplasia C. Acute myeloid leukemia not otherwise categorized D. Acute leukemias of ambiguous lineage

C. Acute megakaryoblastic leukemia, which is equivalent to FAB M7, is a relatively uncommon form of leukemia characterized by neoplastic proliferation of megakaryoblasts and atypical megakaryocytes. Recognition of this entity was aided by the use of platelet peroxidase (PPO) ultrastructural studies. PPO, which is distinct from myeloperoxidase, is specific for the megakaryocytic cell line. Acute megakaryoblastic leukemia is defined as an acute leukemia in which greater than or equal to 50% of the blasts are of megakaryocytic lineage.

Which of the following is a common finding in aplastic anemia? A. A monoclonal disorder B. Tumor infiltration C. Peripheral blood pancytopenia D. Defective DNA synthesis

C. Aplastic anemia has many causes, such as chemical, drug, or radiation poisoning; congenital aplasia; and Fanconi's syndrome. All result in depletion of hematopoietic precursors of all cell lines, leading to peripheral blood pancytopenia.

Which of the following hemoglobins migrates to the same position as Hgb A2 at pH 8.6? A. Hgb H B. Hgb F C. Hgb C D. Hgb S

C. At pH 8.6, several hemoglobins migrate together. These include Hgb A2, Hgb C, Hgb E, Hgb 0Arab, and Hgb CHarlem. These are located nearest the cathode at pH 8.6.

Multiple myeloma is most difficult to distinguish from: A. Chronic lymphocytic leukemia B. Acute myelogenous leukemia C. Benign monoclonal gammopathy D. Benign adenoma

C. Benign monoclonal gammopathies have peripheral blood findings similar to those in myeloma. However, a lower concentration of monoclonal protein is usually seen. There are no osteolytic lesions, and the plasma cells comprise less than 10% of nucleated cells in the bone marrow. About 30% become malignant, and therefore the term monoclonal gammopathy of undetermined significance (MGUS) is the designation used to describe this condition.

Which of the following is not associated with hereditary spherocytosis? A. Increased osmotic fragility B. An MCHC greater than 36% C. Intravascular hemolysis D. Extravascular hemolysis

C. Classic features of intravascular hemolysis such as hemoglobinemia, hemoglobinuria, or hemosiderinuria do not occur in hereditary spherocytosis. The hemolysis seen in hereditary spherocytosis is an extravascular rather than an intravascular process.

A 7.0-mL ethylenediaminetetraacetic acid (EDTA) tube is received in the laboratory containing only 2.0 mL of blood. If the laboratory is using manual techniques, which of the following tests will most likely be erroneous? A. RBC count B. Hemoglobin (Hgb) C. Hct D. WBC count

C. Excessive anticoagulant causes shrinkage of cells; thus, the Hct will be affected. RBC and WBC counts remain the same, as does the Hgb content.

In a patient with human immunodeficiency virus (HIV) infection, one should expect to see: A. Shift to the left in WBCs B. Target cells C. Reactive lymphocytes D. Pelgeroid cells

C. HIV infection brings about several hematological abnormalities seen on peripheral smear examination; most patients demonstrate reactive lymphocytes and have granulocytopenia.

Hereditary pyropoikilocytosis (HP) is a red cell membrane defect characterized by: A. Increased pencil-shaped cells B. Increased oval macrocytes C. Misshapen budding fragmented cells D. Bite cells

C. HP is a membrane defect characterized by a spectrin abnormality and thermal instability. The MCV is decreased and the red cells appear to be budding and fragmented.

In which of the following conditions is Hgb A2 elevated? A. Hgb H B. Hgb SC disease C. β-Thalassemia minor D. Hgb S trait

C. Hgb A2 is part of the normal complement of adult Hgb. This Hgb is elevated in β-thalassemia minor because the individual with this condition has only one normal β-gene; consequently, there is a slight elevation of Hgb A2 and Hgb F.

Hypersplenism is characterized by: A. Polycythemia B. Pancytosis C. Leukopenia D. Myelodysplasia

C. Hypersplenic conditions are generally described by the following four criteria: (1) cytopenias of one or more peripheral cell lines, (2) splenomegaly, (3) bone marrow hyperplasia, and (4) resolution of cytopenia by splenectomy.

SITUATION: The following laboratory values are seen: WBCs = 6.0 × 10^9/L Hgb = 6.0 g/dL RBCs = 1.90 × 10^12/L Hct = 18.5% Platelets = 130 × 10^9/L Serum vitamin B12 and folic acid: normal WBC Differential: 6% PMNs, 40% lymphocytes, 4% monocytes, 50% blasts Bone Marrow: 40% myeloblasts, 60% promegaloblasts, 40 megaloblastoid nRBCs / 100 WBCs These results are most characteristic of: A. Pernicious anemia B. Acute myeloid leukemia without maturation C. Acute erythroid leukemia D. Acute myelomonocytic leukemia

C. In acute erythroid leukemia, more than 50% of nucleated bone marrow cells are erythroid and more than 30% nonerythroid cells are blasts. Pernicious anemia results in pancytopenia and low vitamin B12 concentrations.

All of the following are characteristic findings in a patient with iron deficiency anemia except: A. Microcytic, hypochromic red cell morphology B. Decreased serum iron and ferritin levels C. Decreased total iron-binding capacity (TIBC) D. Increased RBC protoporphyrin

C. In iron deficiency anemia (IDA), there is an increase in TIBC and in RBC protoporphyrin. The serum iron and ferritin levels are decreased. IDA is characterized by a microcytic hypochromic anemia.

"Bite cells" are usually seen in patients with: A. Rh null trait B. Chronic granulomatous disease C. G6PD deficiency D. PK deficiency

C. In patients with G6PD deficiency, the red cells are unable to reduce nicotinamide adenine dinucleotide phosphate (NADP) to NADPH; consequently, Hgb is denatured and Heinz bodies are formed. "Bite cells" appear in the peripheral circulation as a result of splenic pitting of Heinz bodies.

What is the basic hematological defect seen in patients with thalassemia major? A. DNA synthetic defect B. Hgb structure C. β-Chain synthesis D. Hgb phosphorylation

C. In thalassemia major, there is little or no production of the β-chain, resulting in severely depressed or no synthesis of Hgb A. Severe anemia is seen, along with skeletal abnormalities and marked splenomegaly. The patient is usually supported with transfusion therapy.

Calculate the mean cell hemoglobin concentration (MCHC) using the following values: Hgb: 15 g/dL (150 g/L) Hct: 47 mL/dL (0.47) RBC: 4.50 × 106/μL (4.50 × 1012/L) A. 9.5% (.095) B. 10.4% (.104) C. 31.9% (.319) D. 33.3% (.333)

C. MCHC is the average concentration of Hgb in red cells expressed as a percentage. It expresses the ratio of the weight of Hgb to the volume of erythrocytes and is calculated by dividing Hgb by the Hct, and then multiplying by 100. A decreased MCHC indicates that cells are hypochromic. In this example, (15 ÷ 47) × 100 = 31.9%. The reference range for MCHC is 32%-36%.

The macrocytes typically seen in megaloblastic processes are: A. Crescent-shaped B. Teardrop-shaped C. Ovalocytic D. Pencil-shaped

C. Macrocytes in true megaloblastic conditions are oval macrocytes as opposed to the round macrocytes that are usually seen in alcoholism and obstructive liver disease.

Which of the following is an unusual complication that may occur in infectious mononucleosis? A. Splenic infarctions B. Dactylitis C. Hemolytic anemia D. Giant platelets

C. Occasionally patients with infectious mononucleosis develop a potent cold agglutinin with anti-I specificity. This cold autoantibody can cause strong hemolysis and a hemolytic anemia.

The leukocyte alkaline phosphatase (LAP) stain on a patient gives the following results 10(0) 48(1+) 38(2+) 3(3+) 1(4+) Calculate the LAP score. A. 100 B. 117 C. 137 D. 252

C. One hundred mature neutrophils are counted and scored. The LAP score is calculated as: (the number of 1+ cells × 1) + (2+ cells × 2) + (3+ cells × 3) + (4+ cells × 4). That is, 48 + 76 + 9 + 4 = 137. The reference range is approximately 20-130.

The familial condition of Pelger-Huët anomaly is important to recognize because this disorder must be differentiated from: A. Infectious mononucleosis B. May-Hegglin anomaly C. A shift-to-the-left increase in immature granulocytes D. G6PD deficiency

C. Pelger-Huët anomaly is a benign familial condition reported in 1 out of 6,000 individuals. Care must be taken to differentiate Pelger-Huët cells from the numerous band neutrophils and metamyelocytes that may be observed during severe infection or a shift-to-the-left of immaturity in granulocyte stages.

In myeloid cells, the stain that selectively identifies phospholipid in the membranes of both primary and secondary granules is: A. PAS B. Myeloperoxidase C. Sudan Black B stain D. Terminal deoxynucleotidyl transferase (TdT)

C. Phospholipids, neutral fats, and sterols are stained by Sudan Black B. The PAS reaction stains intracellular glycogen. Myeloperoxidase is an enzyme present in the primary granules of myeloid cells and to a lesser degree in monocytic cells. Terminal deoxynucleotidyl transferase is a DNA polymerase found in thymusderived and some bone marrow-derived lymphocytes.

The morphological classification of anemias is based on which of the following? A. M:E (myeloid:erythroid) ratio B. Prussian blue stain C. RBC indices D. Reticulocyte count

C. RBC indices classify the anemia morphologically. Anemias can be classified morphologically by the use of laboratory data; physiologically, based upon the mechanism; and clinically, based upon an assessment of symptoms.

What is the characteristic finding seen in the peripheral smear of a patient with multiple myeloma? A. Microcytic hypochromic cells B. Intracellular inclusion bodies C. Rouleaux D. Hypersegmented neutrophils

C. Rouleaux is observed in multiple myeloma patients as a result of increased viscosity and decreased albumin/globulin ratio. Multiple myeloma is a plasma cell dyscrasia that is characterized by an overproduction of monoclonal immunoglobulin.

The anemia seen in sickle cell disease is usually: A. Microcytic, normochromic B. Microcytic, hypochromic C. Normocytic, normochromic D. Normocytic, hypochromic

C. Sickle cell disease is a chronic hemolytic anemia classified as a normocytic, normochromic anemia.

Which of the following conditions may produce spherocytes in a peripheral smear? A. Pelger-Huët anomaly B. Pernicious anemia C. Autoimmune hemolytic anemia D. Sideroblastic anemia

C. Spherocytes are produced in autoimmune hemolytic anemia. Spherocytes may be produced by one of three mechanisms. First, they are a natural morphological phase of normal red cell senescence. Second, they are produced when the cell surface-to-volume ratio is decreased, as seen in hereditary spherocytosis. And third, they may be produced as a result of antibody coating of the red cells. As the antibody-coated red cells travel through the spleen, the antibodies and portions of the red cell membrane are removed by macrophages. The membrane repairs itself; hence, the red cell's morphology changes from a biconcave disk to a spherocyte.

Given the following values, which set of red blood cell indices suggests spherocytosis? A. MCV 76 μm3 MCH 19.9 pg MCHC 28.5% B. MCV 90 μm3 MCH 30.5 pg MCHC 32.5% C. MCV 80 μm3 MCH 36.5 pg MCHC 39.0% D. MCV 81 μm3 MCH 29.0 pg MCHC 34.8%

C. Spherocytes have a decreased cell diameter and volume, which results in loss of central pallor and discoid shape. The index most affected is the MCHC, usually being in excess of 36%.

Which of the following statistical terms reflects the best index of precision when comparing two CBC parameters? A. Mean B. Median C. Coefficient of variation D. Standard deviation

C. Standard deviation(s) describes the distribution of a sample of observations. It depends upon both the mean (average value) and dispersion of results and is most influenced by reproducibility or precision. Because s is influenced by the mean and expressed as a percentage of the mean, the coefficient of variation ([s ÷ mean] × 100) can be used to compare precision of tests with different means (e.g., WBC and RBC counts or low vs. high controls).

SITUATION: RBC indices obtained on an anemic patient are as follows: MCV 88 μm^3 (fL); MCH 30 pg; MCHC 34% (.340). The RBCs on the peripheral smear would appear: A. Microcytic, hypochromic B. Microcytic, normochromic C. Normocytic, normochromic D. Normocytic, hypochromic

C. The MCV, MCH, and MCHC are all within the reference interval (normal range); hence, the erythrocytes should be of normal size and should reflect normal concentrations of Hgb. Therefore, the anemia is normocytic normochromic.

A striking feature of the peripheral blood of a patient with CML is a: A. Profusion of bizarre blast cells B. Normal number of typical granulocytes C. Presence of granulocytes at different stages of development D. Pancytopenia

C. The WBC count in CML is often higher than 100 × 10^9/L, and the peripheral smear shows a granulocyte progression from myeloblast to segmented neutrophil.

A correction is necessary for WBC counts when nucleated RBCs are seen on the peripheral smear because: A. The WBC count would be falsely lower B. The RBC count is too low C. Nucleated RBCs are counted as leukocytes D. Nucleated RBCs are confused with giant platelets

C. The automated hematology analyzers enumerate all nucleated cells. NRBCs are counted along with WBCs, falsely elevating the WBC count. To correct the WBC count, determine the number of NRBCs per 100 WBCs. Corrected WBC count = (uncorrected WBC count ÷ [NRBC's + 100]) × 100.

A manual WBC count is performed. Eighty WBCs are counted in the four large corner squares of a Neubauer hemacytometer. The dilution is 1:100. What is the total WBC count? A. 4.0 × 10^9/L B. 8.0 × 10^9/L C. 20.0 × 10^9/L D. 200.0 × 10^9/L

C. The formula for calculating manual cell counts using a hemacytometer is: # cells counted × 10 (depth factor) × dilution factor divided by the area counted in mm2, or (80 × 10 × 100) ÷ 4 = 20,000/μL or 20.0 × 109/L

A patient has an Hct of 30%, a hemoglobin of 8 g/dL, and an RBC count of 4.0 × 1012/L. What is the morphological classification of this anemia? A. Normocytic normochromic B. Macrocytic hypochromic C. Microcytic hypochromic D. Normocytic hyperchromic

C. The indices will provide a morphological classification of this anemia. The MCV is 75 fL (reference range 80-100 fL), the MCH is 20.0 pg (reference range 27-31 pg), and the MCHC is 26.6% (reference range 32%-36%). Therefore, the anemia is microcytic hypochromic.

In myelofibrosis, the characteristic abnormal red blood cell morphology is that of: A. Target cells B. Schistocytes C. Teardrop cells D. Ovalocytes

C. The marked amount of fibrosis, both medullary and extramedullary, accounts for the irreversible red cell morphological change to a teardrop shape. The red cells are "teared" as they attempt to pass through the fibrotic tissue.

Repeated phlebotomy in patients with polycythemia vera (PV) may lead to the development of: A. Folic acid deficiency B. Sideroblastic anemia C. Iron deficiency anemia D. Hemolytic anemia

C. The most common treatment modality utilized in PV is phlebotomy. Reduction of blood volume (usually 1 unit of whole blood—450 cc), can be performed weekly or even twice weekly in younger patients to control symptoms. The Hct target range is less than 45% for men, less than 42% for women. Iron deficiency anemia is a predictable complication of therapeutic phlebotomy because approximately 250 mg of iron is removed with each unit of blood.

What is the normal WBC differential lymphocyte percentage (range) in the adult population? A. 5%-10% B. 10%-20% C. 20%-44% D. 50%-70%

C. The normal adult percentage of lymphocytes in a white cell differential is between 20% and 44%, although normal ranges vary by institution, patient population, and testing methodology. This range is higher in the pediatric population.

In leukemia, which term describes a peripheral blood finding of leukocytosis with a shift to the left, accompanied by nucleated red cells? A. Myelophthisis B. Dysplasia C. Leukoerythroblastosis D. Megaloblastosis

C. The presence of immature leukocytes and nucleated red cells is called leukoerythroblastosis and frequently denotes a malignant or myeloproliferative process. Myelophthisis refers to replacement of bone marrow by a disease process such as a neoplasm. The development of abnormal tissue is called dysplasia.

Which of the following are most characteristic of the red cell indices associated with megaloblastic anemias? A. MCV 99 fl, MCH 28 pg, MCHC 31% B. MCV 62 fL, MCH 27 pg, MCHC 30% C. MCV 125 fL, MCH 36 pg, MCHC 34% D. MCV 78 fL, MCH 23 pg, MCHC 30%

C. The red cell indices in a patient with megaloblastic anemia are macrocytic and normochromic. The macrocytosis is prominent, with an MCV ranging from 100 to 130 fL.

Which of the following Hgb configurations is characteristic of Hgb H? A. γ4 B. α2-γ2 C. β4 D. α2-β2

C. The structure of Hgb H is β4. Hgb H disease is a severe clinical expression of α-thalassemia in which only one α-gene out of four is functioning.

A patient's peripheral smear reveals numerous NRBCs, marked variation of red cell morphology, and pronounced polychromasia. In addition to a decreased Hgb and decreased Hct values, what other CBC parameters may be anticipated? A. Reduced platelets B. Increased MCHC C. Increased MCV D. Decreased red-cell distribution width (RDW)

C. This patient's abnormal peripheral smear indicates marked red cell regeneration, causing many reticulocytes to be released from the marrow. Because reticulocytes are larger than mature RBCs, the MCV will be slightly elevated.

Review the following automated CBC values. WBCs = 17.5 × 10^9/L (flagged) RBCs = 2.89 × 10^12/L Hgb = 8.1 g/dL Hct = 25.2% MCV = 86.8 fL MCH = 28.0 pg MCHC = 32.3% PLT = 217 × 10^9/L Many sickle cells were observed upon review of the peripheral blood smear. Based on this finding and the results provided, what automated parameter of this patient is most likely inaccurate and what follow-up test should be done to accurately assess this parameter? A. MCV/perform reticulocyte count B. Hct/perform manual Hct C. WBC/perform manual WBC count D. Hgb/perform serum:saline replacement

C. When an automated WBC count is performed using a hematology analyzer, the RBCs are lysed to allow enumeration of the WBCs. Sickle cells are often resistant to lysis within the limited time frame (less than 1 minute), during which the RBCs are exposed to the lysing reagent and the WBCs are subsequently counted. As a result, the nonlysed RBCs are counted along with the WBCs, thus falsely increasing the WBC count. When an automated cell counting analyzer indicates a review flag for the WBC count, and sickle cells are noted on peripheral smear analysis, a manual WBC count must be performed. The manual method allows optimal time for sickle cell lysis and accurate enumeration of the WBCs.

Which AML cytogenetic abnormality is associated with acute myelomonocytic leukemia with marrow eosinophilia under the WHO classification of AML with recurrent genetic abnormalities? A. AML with t(15;17) B. AML with mixed lineage C. AML with t(8;21) D. AML with inv(16)

D. AML with inv(16) has pericentric inversion of chromosome 16, and is associated with acute myelomonocytic leukemia with marrow eosinophilia, M4eo under the FAB system. The inv(16) results in the fusion of the CBFβ gene on 16q22 with the MYH11 gene on 16p13.

Which type of acute myeloid leukemia is called the true monocytic leukemia and follows an acute or subacute course characterized by monoblasts, promonocytes, and monocytes? A. Acute myeloid leukemia, minimally differentiated B. Acute myeloid leukemia without maturation C. Acute myelomonocytic leukemia D. Acute monocytic leukemia

D. Acute monocytic leukemia has an incidence of between 1%-8% of all acute leukemias. It has a distinctive clinical manifestation of monocytic involvement resulting in skin and gum hyperplasia. The WBC count is markedly elevated, and prognosis is poor.

Which of the following occurs in idiopathic myelofibrosis (IMF)? A. Myeloid metaplasia B. Leukoerythroblastosis C. Fibrosis of the bone marrow D. All of these options

D. Anemia, fibrosis, myeloid metaplasia, thrombocytosis, and leukoerythroblastosis occur in idiopathic myelofibrosis.

Autoagglutination of red cells at room temperature can cause which of the following abnormal test results? A. Low RBC count B. High MCV C. Low hematocrit D. All of these options

D. Autoagglutination at room temperature may cause a low RBC count and high MCV from an electronic counter. The Hct will be low because it is calculated from the RBC count. Low RBC count and low Hct cause falsely high calculations of MCH and MCHC, respectively.

In which of the following conditions will autosplenectomy most likely occur? A. Thalassemia major B. Hgb C disease C. Hgb SC disease D. Sickle cell disease

D. Autosplenectomy occurs in sickle cell anemia as a result of repeated infarcts to the spleen caused by the overwhelming sickling phenomenon.

Which of the morphological findings are characteristic of reactive lymphocytes? A. High nuclear:cytoplasmic ratio B. Prominent nucleoli C. Basophilic cytoplasm D. All of these options

D. Both reactive lymphocytes and blasts may have basophilic cytoplasm, a high N:C ratio, and the presence of prominent nucleoli. Blasts, however, have an extremely fine nuclear chromatin staining pattern as viewed on a Wright's-Giemsa's—stained smear.

Which of the following is (are) commonly found in CML? A. Many teardrop-shaped cells B. Intense LAP staining C. A decrease in granulocytes D. An increase in basophils

D. CML is marked by an elevated WBC count demonstrating various stages of maturation, hypermetabolism, and a minimal LAP staining. An increase in basophils and eosinophils is a common finding. Pseudo-Pelger-Huët cells and thrombocytosis may be present. The marrow is hypercellular with a high M:E ratio (e.g., 10:1).

Which antibiotic(s) is (are) most often implicated in the development of aplastic anemia? A. Sulfonamides B. Penicillin C. Tetracycline D. Chloramphenicol

D. Chloramphenicol is the drug most often implicated in acquired aplastic anemia. About half of the cases occur within 30 days after therapy and about half of the cases are reversible. Penicillin, tetracycline, and sulfonamides have been implicated in a small number of cases.

In which of the following conditions does LAP show the least activity? A. Leukemoid reactions B. Idiopathic myelofibrosis C. PV D. CML

D. Chronic myelogenous leukemia shows the least LAP activity, whereas the LAP score is slightly to markedly increased in each of the other states.

A 24-year-old man with Down syndrome presents with a fever, pallor, lymphadenopathy, and hepatosplenomegaly. His CBC results are as follows: WBCs = 10.8 × 109/L RBCs = 1.56 × 1012/L 8% PMNs Hgb = 3.3 g/dL 25% lymphocytes Hct = 11% 67% PAS-positive blasts Platelets = 2.5 × 109/L These findings are suggestive of: A. Hodgkin's lymphoma B. Myeloproliferative disorder C. Leukemoid reaction D. Acute lymphocytic leukemia

D. Common signs of acute lymphocytic leukemia are hepatosplenomegaly (65%), lymphadenopathy (50%), and fever (60%). Anemia and thrombocytopenia are usually present and the WBC count is variable. The numerous lymphoblasts are generally PAS positive.

Which of the following is considered a normal hemoglobin? A. Carboxyhemoglobin B. Methemoglobin C. Sulfhemoglobin D. Deoxyhemoglobin

D. Deoxyhemoglobin is the physiological Hgb that results from the unloading of oxygen by Hgb. This is accompanied by the widening of the space between β-chains and the binding of 2,3-diphosphoglycerate (2,3-DPG) on a mole-for-mole basis.

Review the following CBC results on a 2-day-old infant: WBCs = 15.2 × 10^9/L RBCs = 5.30 × 10^12/L Hgb = 18.5 g/dL Hct = 57.9% PLT = 213 × 10^9/L MCV = 105 fL MCH = 34.0 pg MCHC = 33.5% These results indicate: A. Macrocytic anemia B. Microcytic anemia C. Liver disease D. Normal values for a 2-day-old infant

D. During the first week of life, an infant has an average Hct of 55 mL/dL. This value drops to a mean of 43 mL/dL by the first month of life. The mean MCV of the first week is 108 fL; after 2 months, the average MCV is 96 fL. The mean WBC count during the first week is approximately 18 × 109/L, and this drops to an average of 10.8 × 109/L after the first month. The platelet count of newborns falls within the same normal range as adults.

Storage iron is usually best determined by: A. Serum transferrin levels B. Hgb values C. Myoglobin values D. Serum ferritin levels

D. Ferritin enters the serum from all ferritin-producing tissues, and therefore is considered to be a good indicator of body storage iron. Because iron stores must be depleted before anemia develops, low serum ferritin levels precede the fall in serum iron associated with iron deficiency anemia.

SITUATION: A differential shows reactive lymphocytes, and the physician suspects a viral infection is the cause. What is the expected laboratory finding in a patient with a cytomegalovirus (CMV) infection? A. Heterophile antibody: positive B. Epstein-Barr virus (EBV)-immunoglobulin (IgM): positive C. Direct antiglobulin test (DAT): positive D. CMV-IgM: positive

D. If both the heterophile antibody test and the EBV-IgM tests are negative in a patient with reactive lymphocytosis and a suspected viral infection, the serum should be analyzed for IgM antibodies to CMV. CMV belongs to the herpes virus family and is endemic worldwide. CMV infection is the most common cause of heterophile-negative infectious mononucleosis.

Iron deficiency anemia may be distinguished from anemia of chronic infection by: A. Serum iron level B. Red cell morphology C. Red cell indices D. Total iron-binding capacity

D. In iron deficiency anemia, the serum iron and ferritin levels are decreased and the total iron-binding capacity and RBC protoporphyrin are increased. In chronic disease, serum iron and TIBC are both decreased because the iron is trapped in reticuloendothelial (RE) cells, and is unavailable to the red cells for hemoglobin production.

Which is the first stage of erythrocytic maturation in which the cytoplasm is pink due to the formation of hemoglobin? A. Reticulocyte B. Pronormoblast C. Basophilic normoblast D. Polychromatic normoblast

D. In normal erythrocytic maturation, Hgb formation in the late polychromatic normoblast stage gives the cytoplasm a prominent pink coloration. The red cell continues to produce Hgb throughout the reticulocyte stage of development.

Which of the following can shift the hemoglobin oxygen dissociation curve to the right? A. Increases in 2,3 DPG B. Acidosis C. Hypoxia D. All of these options

D. Increases in 2,3-DPG, acidosis, hypoxia, and a rise in body temperature all shift the hemoglobin-oxygen dissociation curve to the right. In anemia, although the number of RBCs is reduced, the cells are more efficient at oxygen delivery because there is an increase in red cell 2,3-DPG. This causes the oxyhemoglobin dissociation curve to shift to the right, allowing more oxygen to be released to the tissues.

Which of the following disorders is associated with ineffective erythropoiesis? A. G6PD deficiency B. Liver disease C. Hgb C disease D. Megaloblastic anemia

D. Ineffective erythropoiesis is caused by destruction of erythroid precursor cells prior to their release from the bone marrow. Pernicious anemia results from defective DNA synthesis; it is suggested that the asynchronous development of red cells renders them more liable to intramedullary destruction.

Which morphological classification is characteristic of megaloblastic anemia? A. Normocytic, normochromic B. Microcytic, normochromic C. Macrocytic, hypochromic D. Macrocytic, normochromic

D. Megaloblastic macrocytic anemia is normochromic because there is no defect in the Hgb synthesis. These anemias comprise a group of asynchronized anemias characterized by defective nuclear maturation due to defective deoxyribonucleic acid (DNA) synthesis. This abnormality accounts for the megaloblastic features in the bone marrow and the macrocytosis in the peripheral blood.

Microangiopathic hemolytic anemia is characterized by: A. Target cells and Cabot rings B. Toxic granulation and Döhle bodies C. Pappenheimer bodies and basophilic stippling D. Schistocytes and nucleated RBCs

D. Microangiopathic hemolytic anemia is a condition resulting from shear stress to the erythrocytes. Fibrin strands are laid down within the microcirculation, and red cells become fragmented as they contact fibrin through the circulation process, forming schistocytes.

The pathology of multiple myeloma includes which of the following? A. Expanding plasma cell mass B. Overproduction of monoclonal immunoglobulins C. Production of osteoclast activating factor (OAF) and other cytokines D. All of these options

D. Mutated plasmablasts in the bone marrow undergo clonal replication and expand the plasma cell mass. Normal bone marrow is gradually replaced by the malignant plasma cells leading to pancytopenia. Most malignant plasma cells actively produce immunoglobulins. In multiple myeloma, the normally controlled and purposeful production of antibodies is replaced by the inappropriate production of even larger amounts of useless immunoglobulin molecules. The normally equal production of light chains and heavy chains may be imbalanced. The result is the release of excess free light chains or free heavy chains. The immunoglobulins produced by a clone of myeloma cells are identical. Any abnormal production of identical antibodies is referred to by the general name of monoclonal gammopathy. Osteoclasts are bone cells active in locally resorbing bone and releasing calcium into the blood. Nearby osteoblasts are equally active in utilizing calcium in the blood to form new bone. Multiple myeloma interrupts this balance by the secretion of at least two substances. These are interleukin-6 (IL-6) and osteoclast-activating factor (OAF). As its name implies, OAF stimulates osteoclasts to increase bone resorption and release of calcium, which leads to lytic lesions of the bone.

What phagocytic cells produce lysozymes that are bacteriocidal? A. Eosinophils B. Lymphocytes C. Platelets D. Neutrophils

D. Neutrophils are highly phagocytic and release lysozymes, peroxidase, and pyrogenic proteins. Eosinophils migrate to sites where there is an allergic reaction or parasitic infestation, releasing peroxidase, pyrogens, and other enzymes, including an oxidase that neutralizes histamine. They are poorly phagocytic and do not release lysozyme.

Multiple myeloma and Waldenström's macroglobulinemia have all the following in common except: A. Monoclonal gammopathy B. Hyperviscosity of the blood C. Bence-Jones protein in the urine D. Osteolytic lesions

D. Osteolytic lesions indicating destruction of the bone as evidenced by radiography are seen in multiple myeloma but not in Waldenström's macroglobulinemia. In addition, Waldenström's gives rise to a lymphocytosis that does not occur in multiple myeloma and differs in the morphology of the malignant cells.

Which antibody is associated with paroxysmal cold hemoglobinuria (PCH)? A. Anti-I B. Anti-i C. Anti-M D. Anti-P

D. PCH is caused by the anti-P antibody, a cold autoantibody that binds to the patient's RBCs at low temperatures and fixes complement. In the classic Donath-Landsteiner test, hemolysis is demonstrated in a sample placed at 4°C that is then warmed to 37°C.

A 50-year-old patient is suffering from pernicious anemia. Which of the following laboratory data are most likely for this patient? A. RBC = 2.5 × 10^12/L; WBC =12,500/μL (12.5 × 10^9/L); PLT = 250,000/μL (250 × 10^9/L) B. RBC = 4.5 × 10^12/L; WBC = 6,500/μL (6.5 × 10^9/L); PLT = 150,000/μL (150 × 10^9/L) C. RBC = 3.0 × 10^12/L; WBC = 5,000/μL (5.0 × 10^9/L); PLT = 750,000/μL (750 × 10^9/L) D. RBC = 2.5 × 10^12/L; WBC = 2,500/μL (2.5 × 10^9/L); PLT = 50,000/μL (50 × 10^9/L)

D. Patients with pernicious anemia demonstrate a pancytopenia with low WBC, PLT, and RBC counts. Because this is a megaloblastic process and a DNA maturation defect, all cell lines are affected. In the bone marrow, this results in abnormally large precursor cells, maturation asynchrony, hyperplasia of all cell lines, and a low M:E ratio.

Which of the following is the primary Hgb in patients with thalassemia major? A. Hgb D B. Hgb A C. Hgb C D. Hgb F

D. Patients with thalassemia major are unable to synthesize the β-chain; hence, little or no Hgb A is produced. However, γ-chains continue to be synthesized and lead to variable elevations of Hgb F in these patients.

Which anemia is characterized by a lack of intrinsic factor that prevents B12 absorption? A. Tropical sprue B. Transcobalamin deficiency C. Blind loop syndrome D. Pernicious anemia

D. Pernicious anemia is caused by a lack of intrinsic factor, which prevents vitamin B12 absorption.

A manual RBC count is performed on a pleural fluid. The RBC count in the large center square of the Neubauer hemacytometer is 125, and the dilution is 1:200. What is the total RBC count? A. 27.8 × 10^9/L B. 62.5 × 10^9/L C. 125.0 × 10^9/L D. 250.0 × 10^9/L

D. Regardless of the cell or fluid type, the formula for calculating manual cell counts using a hemacytometer is: # cells counted × 10 (depth factor) × dilution factor divided by the area counted in mm2, or (125 × 10 × 200) ÷ 1 = 250,000/μL or 250.0 × 109/L

Reticulocytosis usually indicates: A. Response to inflammation B. Neoplastic process C. Aplastic anemia D. Red cell regeneration

D. Reticulocytes are polychromatophilic macrocytes, and the presence of reticulocytes indicates red cell regeneration. The bone marrow's appropriate response to anemia is to deliver red cells prematurely to the peripheral circulation. In this way, reticulocytes and possibly nucleated red cells may be seen in the peripheral smear.

All of the following are associated with sideroblastic anemia except: A. Increased serum iron B. Ringed sideroblasts C. Dimorphic blood picture D. Increased RBC protoporphyrin

D. Sideroblastic anemia has a decreased red cell protoporphyrin. The defect in sideroblastic anemia involves ineffective erythropoiesis. The failure to produce RBC protoporphyrin occurs because the nonheme iron is trapped in the mitochondria and is unavailable to be recycled.

When an erythrocyte containing iron granules is stained with Prussian blue, the cell is called a: A. Spherocyte B. Leptocyte C. Schistocyte D. Siderocyte

D. Siderocytes are red cells containing iron granules and are visible when stained with Prussian blue.

Spherocytes differ from normal red cells in all of the following except: A. Decreased surface to volume B. No central pallor C. Decreased resistance to hypotonic saline D. Increased deformability

D. Spherocytes lose their deformability owing to the defect in spectrin, a membrane protein, and are therefore prone to splenic sequestration and hemolysis.

Which of the following disorders has an increase in osmotic fragility? A. Iron deficiency anemia B. Hereditary elliptocytosis C. Hereditary stomatocytosis D. Hereditary spherocytosis

D. Spherocytic cells have decreased tolerance to swelling and, therefore, hemolyze at a higher concentration of sodium salt compared with normal red cells.

Which of the following is often associated with CML but not with AML? A. Infections B. WBCs greater than 20.0 × 109/L C. Hemorrhage D. Splenomegaly

D. Splenomegaly is seen in more than 90% of CML patients, but it is not a characteristic finding in AML. Infections, hemorrhage, and elevated WBC counts may be seen in both CML and AML.

All of the following are usually found in Hgb C disease except: A. Hgb C crystals B. Target cells C. Lysine substituted for glutamic acid at the sixth position of the β-chain D. Fast mobility of Hgb C at pH 8.6

D. Substitution of a positively charged amino acid for a negatively charged amino acid in Hgb C disease results in a slow electrophoretic mobility at pH 8.6

A patient's peripheral blood smear and bone marrow both show 70% blasts. These cells are negative for Sudan Black B stain. Given these data, which of the following is the most likely diagnosis? A. Acute myeloid leukemia B. Chronic lymphocytic leukemia C. Acute promyelocytic leukemia D. Acute lymphocytic leukemia

D. Sudan Black B stains phospholipids and other neutral fats. It is the most sensitive stain for granulocytic precursors. Lymphoid cells rarely stain positive for it. Because 70% lymphoblasts would never be seen in CLL, the correct response is ALL.

Which of the following leukemias are included in the 2008 World Health Organization classification of myeloproliferative neoplasms? A. Chronic myelogenous leukemia (CML) B. Chronic neutrophilic leukemia (CNL) C. Chronic eosinophilic leukemia (CEL) D. All of these options are classified as myeloproliferative neoplasms (MPN)

D. The 2008 WHO classification system includes the following disorders under the myeloproliferative neoplasms (MPN): chronic myelogenous leukemia (CML), chronic neutrophilic leukemia (CNL), chronic eosinophilic leukemia (CEL), essential thrombocythemia (ET), polycythemia vera (PV), primary (idiopathetic) myelofibrosis, hypereosinophilic syndrome, mast cell disease, and MPNs unclassified.

The JAK2(V617F) mutation may be positive in all of the following chronic myeloproliferative disorders except: A. Essential thrombocythemia B. Idiopathic myelofibrosis C. PV D. CML

D. The JAK2(V617F) mutation is negative in patients with CML. It may be positive in patients with idiopathic myelofibrosis (35%-57%), polycythemia vera (65%-97%), and essential thrombocythemia (23%-57%).

All of the following are associated with the diagnosis of multiple myeloma except: A. Marrow plasmacytosis B. Lytic bone lesions C. Serum and/or urine M component (monoclonal protein) D. Philadelphia chromosome

D. The Ph1 chromosome is a diagnostic marker for CML. Osteolytic lesions, monoclonal gammopathy, and bone marrow infiltration by plasma cells constitute the triad of diagnostic markers for multiple myeloma.

An autohemolysis test is positive in all the following conditions except: A. Glucose-6-phosphate dehydrogenase (G6PD) deficiency B. Hereditary spherocytosis (HS) C. Pyruvate kinase (PK) deficiency D. Paroxysmal nocturnal hemoglobinuria (PNH)

D. The autohemolysis test is positive in G6PD and PK deficiencies and in HS, but is normal in PNH because lysis in PNH requires sucrose to enhance complement binding. The addition of glucose, sucrose, or adenosine triphosphate (ATP) corrects the autohemolysis of HS. Autohemolysis of PK can be corrected by ATP.

All of the following are major criteria for the 2008 WHO diagnostic criteria for essential thrombocythemia except: A. Platelet count >450 × 109/L B. Megakaryocyte proliferation with large and mature morphology, and no or little granulocyte or erythroid proliferation C. Demonstration of JAK2(V617F) or other clonal marker D. Sustained platelet count >600 × 109/L

D. The criterion for the 2001 WHO diagnosis of essential thrombocythemia (ET) was a platelet count ≥600 x 109/L. This was changed in the 2008 WHO criteria to ≥450 x 109 /L. Diagnosis of essential thrombocythemia requires meeting all four major 2008 WHO diagnostic criteria, which also includes: megakaryocyte proliferation with large and mature morphology and no or little granulocyte or erythroid proliferation; not meeting WHO criteria for CML, PV, IMF, MDS, or other myeloid neoplasm; and demonstration of JAK2(V617F) mutation or other clonal marker, or no evidence of reactive thrombocytosis.

PV is characterized by: A. Increased plasma volume B. Pancytopenia C. Decreased oxygen saturation D. Absolute increase in total red cell mass

D. The diagnosis of PV requires the demonstration of an increase in red cell mass. Pancytosis may also be seen in about two thirds of PV cases. The plasma volume is normal or slightly reduced, and the arterial oxygen saturation is usually normal.

Hemolytic uremic syndrome (HUS) is characterized by all of the following except: A. Hemorrhage B. Thrombocytopenia C. Hemoglobinuria D. Reticulocytopenia

D. The hemolytic anemia of HUS is associated with reticulocytosis. The anemia seen in HUS is multifactorial, with characteristic schistocytes and polychromasia commensurate with the anemia.

Which is the major Hgb found in the RBCs of patients with sickle cell trait? A. Hgb S B. Hgb F C. Hgb A2 D. Hgb A

D. The major hemoglobin in sickle cell trait is Hgb A, which constitutes 50%-70% of the total. Hgb S comprises 20%-40%, and Hgb

Leukemic lymphoblasts reacting with anti-CALLA are characteristically seen in: A. B-cell ALL B. T-cell ALL C. Null-cell ALL D. Common ALL

D. The majority of non-T, non-B ALL blast cells display the common ALL antigen (CALLA) marker. Lymphoblasts of common ALL are TdT positive and CALLA positive but do not have surface membrane IgM or μ chains and are pre-B lymphoblasts. Common ALL has a lower relapse rate and better prognosis than other immunologic subtypes of B-cell ALL.

What is the typical range of relative lymphocyte percentage in the peripheral blood smear of a 1-year-old child? A. 1%-6% B. 27%-33% C. 35%-58% D. 50%-70%

D. The mean relative lymphocyte percentage for a 1-year-old child is 61% compared to the mean lymphocyte percentage of 35% for an adult.

Which of the following cells is considered pathognomonic for Hodgkin's disease? A. Niemann-Pick cells B. Reactive lymphocytes C. Flame cells D. Reed-Sternberg cells

D. The morphological common denominator in Hodgkin's lymphoma is the Reed-Sternberg (RS) cell. It is a large, binucleated cell with a dense nucleolus surrounded by clear space. These characteristics give the RS cell an "owl's eye" appearance. Niemann-Pick cells (foam cells) are histiocytes containing phagocytized sphingolipids that stain pale blue and impart a foamlike texture to the cytoplasm. Flame cells are plasma cells with distinctive red cytoplasm. They are sometimes seen in the bone marrow of patients with multiple myeloma.