Hematology:: Blood Smears
Beta thalassemia major
A blood disorder, caused by point mutations in the splice sites or promoter sequences of HBB gene, decreasing beta-globin synthesis. beta-globin is absent, leading to severe microcytic/hypochromic anemia with target cells and anisopoikilocytosis. Requires blood transfusions. HbF protects infants and pushes diagnosis to after the 6-month mark. Microcytic, hypochromic anemia.
Sideroblastic anemia
Anemia with increased iron, increased ferritin, decreased TIBC. Ringed sideroblasts with blue-stained mitochondria in bone marrow. Basophilic stippling in peripheral blood smear. Can be genetic (x-linked defect in ALA synthase), acquired, or reversible (alcoholism, vitamin B6 deficiency, copper deficiency). Treated with pyridoxine. Microcytic, hypochromic anemia.
Autoimmune hemolytic anemia
Antibodies self-reactive against RBCs cause RBC lysis. Decreases longevity of RBCs from 120 days to a couple of weeks. Can be caused by medications, which bind to RBCs and are targeted by host antibodies. Can be associated with other autoimmune disorders or can be an independent disorder.
Echinocytes (blood smear description)
Burr cells, have small regular bumpy protrusions from the cell surface, makes them look kind of like gears. Seen in renal disease/failure
Iron deficiency anemia
Decreased iron due to chronic bleeding, malnutrition, absorption disorders, GI surgery, or pregnancy, which leads to decreased heme synthesis. Decreased iron, and ferritin. Increased free erythrocyte protoporphyrin and total iron binding capacity (TIBC). Symptoms are fatigue, pallor, pica, and spoon nails. Microcytic, hypochromic RBCs
Extrinsic vs. intrinsic hemolytic anemia?
Extrinsic is autoimmune attack on otherwise healthy RBCs. Intrinsic hemolytic anemia is defective production of RBCs.
Sickle Cell Anemia
HbS instead of HbA. Point mutation causes messed up beta chain of hemoglobin. Leads to extravascular and intravascular hemolysis. Cells are rigid and irregularly shaped, and can become trapped in blood vessels, causing sickle crises. Increases risk of splenic sequestration, renal papillary necrosis. Treat with hydroxyurea, which increases production of fetal hemoglobin (fetal hemoglobin is immune to point mutation that creates HbS)
Hereditary spherocytosis
Hemolytic anemia caused by defect in proteins in RBC membrane skeleton/plasma membrane (ankyrin, band 3, spectrin, protein 4.2). Autosomal dominant. Results in mycrocytic, spherical RBCs with less surface area (there's no concavity) and no central pallor. Leads to premature removal of RBCs by spleen. Symptoms = splenomegaly, aplastic crisis (cessation of RBC production caused by parovirus B19 infection). Decreased MCV of RBCs but a bunch of RBCs present. Treat by removing spleen.
Hemoglobin C
Hemolytic anemia, caused by glu (e) to lys (k) mutation in beta-globin. Causes extravascular hemolysis (lysing of RBCs by spleen or liver, not in circulation). Will see target cells and crystals inside RBCs in blood smear.
Iron deficiency anemia (blood smear description)
Hypochromic (pale), microcytotic (small) RBCs with increased number of platelets
Lead poisoning
Lead inhibits ferrochelatase and ALA dehydratase, decreasing heme synthesis and increasing RBC protoporphyrin. Lead also inhibits rRNA degradation, leading to basophilic stippling of RBCs. You'll see abdominal colic (cramping), encephalopathy (change in brain function), wrist and foot drop, sideroblastic anemia, and lead lines along the metaphyses (ends) of bones. Microcytic, hypochromic anemia.
Hypo-albuminemia
Low level of albumin, a plasma protein, in the blood. Can be caused by liver failure/cirrhosis (albumin is made in the liver). You'll see swelling, altered drug/hormone efficacy. Peripheral blood smear shows rouleaux (caterpillar line of RBCs)
Megaloblastic Anemia (blood smear description)
Macrocytic RBCs + neutrophils with hypersegmented nuclei
Megaloblastic Anemia
Macrocytic anemia, caused by impaired DNA synthesis. Nucleus of precursor cell develops slower than cytoplasm. Leads to hypersegmented neutrophils as well. Caused by foate deficiency, vitamin b12 deficiency, orotic aciduria.
Multiple Myeloma
Monoclonal plasma cell cancer seen in bone marrow. Leads to big increase in IgG or IgA present in body. Symptoms: hypercalcemia, renal issues, anemia, bone lytic lesions, back pain.
Waldenstrom's macroglobulinemia
Non-hodgkin B-cell lymphoma with excess production of an abnormal protein macroglobulin. Cancer cells have features of both B cells and plasma cells. Buildup of monoclonal antibody macroglobulin leads to symptoms of excess bleeding, problems with vision and CNS, anemia, hepatosplenomegaly. Rouleaux are seen with this cancer.
AIHA (description)
Polychromasia and microspherocytes
Schistocytes (blood smear description)
RBC fragments with rough broken edges. Associated with Microangiopathic Hemolytic Anemia (MAHA)
RBC agglutination (blood smear description)
RBCs are coated with IgM. IgM is big enough as a pentamer to bind to at least 2 RBCs at once, leading to clusters. Clusters of RBCs, non-ordered
Microangiopathic hemolytic anemia (maha)
RBCs are damaged when passing through blocked or narrowed blood vessels. You'll see schistocytes (schism, broken) in peripheral blood smear because damage is mechanical. Can be seen in hemolytic uremic syndrome.
Hypochromasia (blood smear description)
RBCs have too little hemoglobin, so they're paler than normal on the inside. Measured by Mean Corpuscular Hemoglobin
Macrocytosis (blood smear description)
RBCs that are bigger than normal. Seen in B12/folate deficiency, liver disease, thyroid disease, with use of chemotherapy and anti-retrovirals (zidovudine), aplastic anemia
Polychromasia (blood smear description)
RBCs that are blueish, usually a bit bigger than healthy reticulocytes. They have less of a pale interior.
Microcytosis (blood smear description)
RBCs that are smaller than normal. Seen in iron deficiency, thalassemias, lead poisoning, and sideroblastic anemia.
Target Cells (blood smear description)
RBCs that look like a target, with a red exterior, a white band, and a red dot in the middle. Associated with liver disease, thalassemia, hemoglobin C disease.
Poikilocytosis (blood smear description)
RBCs that vary significantly in shape
Anisocytosis (blood smear description)
Red cells which vary in size
Teardrop cells (blood smear description)
Seen in myelophthisic processes, or bone marrow infiltration diseases. Cells are almost conical. Seen in myelofibrosis, tumor metastases in bone marrow, granulomatous disease, leukemias and lymphomas.
Sickle Cell (blood smear description)
Seen in sickle cell anemia, associated with a point mutation in the hemoglobin protein. It leads to chains of hemoglobin in the blood cell, which forces the cell into a sickle shape. The sickle shape is much less flexible and is punctured more often than healthy RBCs.
Howell-Jolly Bodies (blood smear description)
Small dark purple dots seen inside blood cells. These are remnants of the nucleus. Typically seen after splenectomy or in cases of decreased spleen function.
Spherocytes (blood smear description)
Spherical blood cells with a loss of central pallor. Seen in hereditary spherocytosis (cytoskeletal issue), and autoimmune hemolysis (in autoimmune hemolysis the RBCs are also microcytotic)
Acanthocytes (blood smear description)
Spur cells (look like funky cowboy spurs), have large, irregular protrusions, like long thin spikes, poking out of the cell surface. Seen in liver disease.
Beta-thalassemia major (blood smear description)
Target cells, howell jolly bodies, nucleated RBCs, Schisocytes, Basophilic Stippling (presence of multiple small purple dots, likely ribosomes or proteins, in RBC, maybe Teardrops
Red Cell Distribution Width
Variation in RBC volume within a person.
Which anemias are microcytic/hypochromic?
alpha/beta thalassemia, iron deficiency, lead poisoning, sideroblastic anemia.
Rouleaux (blood smear description)
caterpillar-like linear clusters of RBCs. Seen in multiple myeloma, Waldenstrom's macroglobulinemia, and severe hypo-albuminemia
