chapter 22: BM failure

DKC treatment and prognosis

-Median survival for patients with DKC is 42 years -60% to 70% of deaths are due to bone marrow failure complications. Ten percent to 15% of deaths result from severe pulmonary disease, and 10% of deaths result from malignancies -Treatment with bone marrow transplantation has not been optimal because of the high incidence of fatal pulmonary fibrosis and vascular complications -androgen therapy produces a transient response in 50% to 70% of patients, it does not halt the progression of the bone marrow failure

cytogenic analysis in aplastic anemia

-Monosomy 7 and trisomy 8 are the most common -using conventional culture techniques often underestimates the incidence of karyotype abnormalities because of bone marrow hypocellularity and scarcity of cells in metaphase

DKC lab findings

-Pancytopenia and macrocytic RBCs are typical peripheral blood findings -fetal hemoglobin level may also be increased -about 40% of patients have an identified mutation in one of the eight known telomerase complex genes -new flow fluorescence in situ hybridization (FISH) test for detection of very short telomeres in WBC subsets has been proposed as a diagnostic test for those with suspected DKC who lack mutations in known genes -Patients with FA, SBDS, and acquired aplastic anemia may also have cells with shortened telomeres, though they are not found in multiple WBC subsets -DKC cells often have shortened telomeres in several WBC subsets, including naive T cells and B cells

antibiotic and antifungal prophylaxis in cases of prolonged neutropenia

-Patients with mild to moderate aplastic anemia may not require treatment but must be monitored periodically for pancytopenia and abnormal cells

SBDS genetic and pathophysiology

-an autosomal recessive disorder, and 90% of patients have biallelic mutations in the SBDS gene -gene is involved in ribosome metabolism and mitotic spindle stability its relationship to the disease manifestations is currently unknown -There are quantitative and qualitative deficiencies in CD341 cells, dysfunctional bone marrow stromal cells, increased apoptosis and mitotic spindle destabilization in hematopoietic cells, and short telomeres in peripheral blood granulocytes

differentiation between acquired and inherited aplastic anemia has important implications for?

-appropriate treatment and prognosis 1. Immunosuppressive therapy is not nearly as effective in inherited aplastic anemia as it is in acquired aplastic anemia 2.hematopoietic stem cell transplantation (HSCT), the only known curative treatment for DKC and SBDS and a treatment option for acquired aplastic anemia, should not be performed with human leukocyte antigen (HLA)-matched siblings who test positive for the same genetic mutation 3. shortened telomeres occur more often in patients whose pancytopenia does not respond to immunosuppressive therapy

aplastic anemia incidence

-approximately 1 in 500,000 -Asia and East Asia, the incidence is two to three times higher than in North America or Europe, which may be due to environmental and/or genetic differences -Aplastic anemia can occur at any age, with peak incidence at 15 to 25 years and the second highest frequency at greater than 60 years -no gender predisposition

pathophysiology of BM includes

1. the destruction of hematopoietic stem cells due to injury by drugs, chemicals, radiation, viruses, or autoimmune mechanisms 2.premature senescence and apoptosis of hematopoietic stem cells due to genetic mutations 3.ineffective hematopoiesis due to stem cell mutations or vitamin B12 or folate deficiency 4. disruption of the bone marrow microenvironment that supports hematopoiesis 5.decreased production of hematopoietic growth factors or related hormones 6.the loss of normal hematopoietic tissue due to infiltration of the marrow space with abnormal cells

acquired aplastic anemia major categories

1.idiopathic: no known cause -70% of all aplastic anemia cases are idiopathic, whereas 10% to 15% are secondary 2.secondaary acquired aplastic anemia: identified cause *both have similar clinical and laboratory findings, Patients may initially present with macrocytic or normocytic anemia and reticulocytopenia. Pancytopenia may develop slowly or progress at a rapid rate, with complete cessation of hematopoiesis

aplastic anemia pathophysiology

1.primary lesion: quantitative and qualitative deficiency of hematopoietic stem cells 2.Stem cells of patients with acquired aplastic anemia have diminished colony formation in methylcellulose cultures -hematopoietic stem and early progenitor cell compartment is identified by expression of CD34 surface antigens. The CD34+ cell population in the bone marrow of patients with acquired aplastic anemia can be 10% or lower than that seen in healthy individuals. -these CD341 cells have increased expression of Fas receptors that mediate apoptosis and increased expression of apoptosis-related genes 3. bone marrow stromal cells are functionally normal in acquired aplastic anemia. -They produce normal or even increased quantities of growth factors and are able to support the growth of CD34+ cells from healthy donors in culture and in vivo after transplantation 4.elevated serum levels of erythropoietin, thrombopoietin, granulocyte colony-stimulating factor (G-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) -serum levels of FLT3 ligand, a growth factor that stimulates proliferation of stem and progenitor cells, is up to 200 times higher in patients with severe aplastic anemia compared to healthy controls -despite their elevated levels, growth factors are generally unsuccessful in correcting the cytopenias found in acquired aplastic anemia

Dyskeratosis congenita (DKC)

rare inherited bone marrow failure syndrome with fewer than 600 known cases worldwide

treatment in aplastic anemia

*Blood product replacement should be given judiciously to avoid alloimmunization. *Platelets should not be transfused at levels greater than 10,000/mL, unless the patient is bleeding

autoimmune mechanisms

*include mutation of stem cell antigens and disruption of immune regulation *environmental exposures: may alter self-proteins, induce expression of abnormal or novel antigens, or induce an immune response that cross-reacts with self-antigens *CD4+CD25+FOXP3+ regulatory T cells are decreased in aplastic anemia: These regulatory T cells normally suppress autoreactive T cells, and a deficit of these cells may facilitate an autoimmune reaction *some individuals: aplastic anemia have single nucleotide polymorphisms in IFN-g/1874 TT, TNF-a/-308 AA, transforming growth factorb1/- 509 TT, and interleukin-6/-174 GG -These polymorphisms result in cytokine overproduction and may impart a genetic susceptibility to aplastic anemia as well as contribute to its severity

outcome in patients with acquired aplastic anemia

*patients who receive an HSCT from an HLA-identical sibling, 91% of children and 74% of adults achieve 10-year overall survival. *50 Those percentages decrease slightly to 75% of children and 63% of adults when the bone marrow transplant is from an HLA-matched unrelated donor.50 In patients treated with IST, 75% of children and 63% of adults achieve 10-year survival

Decreased RBCs and hemoglobin can result in?

fatigue, pallor, and cardiovascular complications

Schwachman-Bodian-Diamond Syndrome

inherited multisystem disorder characterized by pancreatic insufficiency, cytopenia, skeletal abnormalities, and a predisposition for hematologic malignancies *estimated to be approximately 8.5 cases per 1 million live births

proteins expressed in hematopoeitc progenitor cells in aplastic anemia

responsible for triggering and sustaining the autoimmune attack on stem cells are unknown. Candidate antigens have been identified from aplastic anemia patient sera, including kinectin,35 diazepam-binding inhibitor-related protein 1,36 and moesin

BM failure is

the reduction or cessation of blood cell production affecting one or more cell lines

interphase fluorescence in situ hybridization (FISH) in aplastic anemia

using deoxyribonucleic acid (DNA) probes for specific chromosome abnormalities may be used

thrombocytopenia

-result in bleeding and increased bruising -

fanconi genetics and pathophysiology

-15 genes: FANCA, FANCB, FANCC, FANCD1 (also called BRCA2), FANCD2, FANCE, FANCF, FANCG (also called XRCC9), FANCI, FANCJ (also called BRIP1/ BACH1), FANCL, FANCM, FANCN (also called PALB2), FANCO (also called RAD51C), and FANCP (also called SLX4) -Patients with FA typically have biallelic mutations or deletions in one of these genes -mode of inheritance is autosomal recessive except for FANCB, which is X-linked recessive -Mutations in the FANCA gene occur with the highest frequency -Patients with FA typically have biallelic mutations or deletions in one of these genes -mode of inheritance is autosomal recessive except for FANCB, which is X-linked recessive -Mutations in the FANCA gene occur with the highest frequency -Cells are highly susceptible to chromosome breakage after exposure to DNA cross-linking agents. FA cells may also have accelerated telomere shortening and apoptosis, a late S-phase cell cycle delay, hypersensitivity to oxidants, and cytokine dysregulation -range of FA protein function is not completely known, but these proteins participate in a highly elaborate DNA damage response pathway -FA pathway consists of a nuclear core complex, a protein ID complex, and effector proteins -FA proteins A, B, C, E, F, G, L, and M form the nuclear core complex; proteins D2 and I form the ID complex; and the effector proteins are D1, J, N, O, and P -The core complex facilitates the monoubiquitylation and activation of the ID complex. The ID complex then localizes with effector DNA repair proteins at foci of DNA damage to effect DNA repair

Shwachman-Bodian-Diamond syndrome (SBDS) gene

-4% of patients with acquired aplastic anemia and shortened telomeres have mutations in this gene -product is involved in ribosome biogenesis, and its relationship to telomere maintenance is currently unknown -TERT/TERC and SBDS mutations also occur in the inherited aplastic anemias, dyskeratosis congenita (DKC) and SBDS, respectively, and some patients diagnosed with acquired aplastic anemia who have these mutations may actually have DKC or SBDS. -

fanconi treatment and prognosis

-90% of FA patients develop bone marrow failure by 40 years of age -one third of patients develop MDS and/or acute myeloid leukemia (AML) by a median age of 14 years, and 25% develop solid tumors by a median age of 26 years -Squamous cell carcinomas of the head and neck, anogenital region, and skin are the most common solid tumors, followed by tumors of the liver, brain, and kidney -have an increased risk of developing vulvar cancer (4300-fold), esophageal cancer (2300-fold), AML (800-fold), and head/neck cancer (700-fold) compared with the general population -3% of patients develop more than one type of malignancy -if left untreated, death by 20 years of age secondary to bone marrow failure or malignancy is common -Patients with mutations in the FANCC gene experience bone marrow failure at a particularly young age and have the poorest survival -Increased telomere shortening in FA cells is associated with more severe pancytopenia and a higher risk of malignancy -the precise role of telomere shortening in the evolution of bone marrow failure and cancer is currently unclear -Supportive treatment for cytopenia includes transfusions and administration of cytokines (G-CSF and GM-CSF) -only curative treatment is HSCT, preferably from an HLAidentical sibling. It is important to screen donor siblings for FA prior to transplant. Patients should also have decreased intensity pretransplant conditioning because of their underlying chromosomal instability

DKC genetics and pathophysiology

-DKC chromosomes have very short telomeres, and inherited defects in the telomerase complex -telomerase complex synthesizes telomere repeats to elongate chromosome ends, maintaining the telomere length needed for cell survival -eight different genes implicated in DKC, and it can be inherited in three different patterns: X-linked recessive, autosomal dominant, and autosomal recessive -best-characterized form results from one or more mutations on the long arm of the X-chromosome on the DKC1 gene dyskerin -Dyskerin is a ribonucleoprotein involved in RNA processing, and it associates with TERC (telomerase RNA component) in the telomerase complex -The autosomal dominant form is due to mutations in the genes that encode TERC, TERT (telomerase enzyme), or TINF2 (component of the shelterin complex that regulates telomere length) -autosomal recessive form, mutations in TERT, NHP2, NOP10, WRAP53, and CTC1 have been identified -proteins encoded by these genes are also involved in telomere maintenance -exact pathophysiologic mechanisms are still unknown, the shortened telomeres in DKC cause premature death in the rapidly dividing cells in the bone marrow and epithelium and likely lead to genomic instability and a predisposition to cancer

FISH vs. cytogenic analysis

-FISH has greater sensitivity in the detection of chromosome abnormalities and can also be performed using nondividing cells

fanconi clinical findings

-Physical malformations may be present at birth, though hematologic abnormalities may not appear until older childhood or adulthood -only two thirds of patients have physical malformations -These anomalies vary considerably, though there is a higher frequency of skeletal abnormalities (thumb malformations, radial hypoplasia, microcephaly, hip dislocation, and scoliosis); skin pigmentation (hyperpigmentation, hypopigmentation, café-au-lait lesions) short stature; and abnormalities of the eyes, kidneys, and genitals -Low birth weight and developmental delay are also common -symptoms associated with pancytopenia usually become apparent at 5 to 10 years of age, though some patients may not present until adulthood -increased cancer risk -includes an increased incidence of leukemia in childhood and solid tumors (e.g., oral, esophageal, anogenital, cervical) in adulthood -approximately 5% of cases, a malignancy is diagnosed before the FA is recognized

congenital dyserythropoietic anemia (CDAs)

-are a heterogeneous group of rare disorders characterized by refractory anemia, reticulocytopenia, hypercellular bone marrow with markedly ineffective erythropoiesis, and distinctive dysplastic changes in bone marrow erythroblasts -Megaloblastoid development occurs in some types, but it is not related to vitamin B12 or folate deficiency -Granulopoiesis and thrombopoiesis are normal -anemia varies from mild to moderate, even among affected siblings -Secondary hemosiderosis arises fromchronic intramedullary and extramedullary hemolysis, as wellas increased iron absorption associated with ineffective erythropoiesis -Iron overload develops even in the absence of blood transfusions. Jaundice, cholelithiasis, and splenomegaly are also common findings. CDAs do not progress to aplastic anemia or hematologic malignancies -Symptoms of CDA usually occur in childhood or adolescence but may first appear in adulthood -CDA is classified into three major types: CDA I, CDA II, and CDA III -four other groups: CDA IV through CDA VII -CDA types IV through VII actually are separate entities is a matter of some controversy. This merely may be a reflection of the insensitive tests to classify CDA disorders -

secondary aplastic anemia

-associated with exposure to certain drugs, chemicals, radiation, or infections -Cytotoxic drugs, radiation, and benzenes are responsible for 10% of secondary aplastic anemia cases and suppress the bone marrow in a predictable, dose-dependent manner -Depending on the dose and exposure duration, the bone marrow generally recovers after withdrawal of the agent -approximately 70% of cases of secondary aplastic anemia occur due to idiosyncratic reactions to drugs or chemicals. In idiosyncratic reactions, the bone marrow failure is unpredictable and unrelated to dose -evidence is primarily circumstantial and symptoms may occur months or years after exposure -is a rare event and is likely due to a combination of genetic and environmental factors in susceptible individuals

symptoms in aplastic anemia

-asymptomatic to severe -insidious-onset anemia, with pallor, fatigue, and weakness -severe and prolonged: result in serious cardiovascular complications, including tachycardia, hypotension, cardiac failure, and death -thrombocytopenia: include petechiae, bruising, epistaxis, mucosal bleeding, menorrhagia, retinal hemorrhages, intestinal bleeding, and intracranial hemorrhage -Fever and bacterial or fungal infections are unusual at initial presentation but may occur after prolonged periods of neutropenia. -Splenomegaly and hepatomegaly are typically absent

DKC clinical findings

-characterized by mucocutaneous abnormalities, bone marrow failure, and pancytopenia -involves a triad of abnormal skin pigmentation, dystrophic nails, and oral leukoplakia -Skin and nail findings usually appear before 10 years of age -Median age of diagnosis is 15 years -30 years of age, 80% to 90% of patients have bone marrow abnormalities -Patients can also manifest a wide range of multisystem abnormalities, including pulmonary fibrosis, liver disease, developmental delay, short stature, microcephaly, prematurely gray hair or hair loss, immunodeficiency, dental caries, and periodontal disease -Patients have a 40% risk of cancer by 50 years of age, most commonly AML, MDS, and epithelial malignancies

PRCA may occur in?

-children or adults -acute or chronic -primary PRCA can be idiophatic or auto-immune related -secondary: association with an underlying thymoma, hematologic malignancy, solid tumor, infection, chronic hemolytic anemia, collagen vascular disease or expose to drugs or chemicals -Therapy is first directed at treatment of the underlying condition, but immunosuppressive therapy may be considered if the PRCA is not responsive -Cyclosporine is associated with a higher response rate (65% to 87%) than corticosteroids (30% to 62%) and is better suited for long-term maintenance if needed -acquired form of PRCA in young children is also known as transient erythroblastopenia of childhood (TEC) -history of viral infection is found in half of patients, which is thought to trigger an immune mechanism that targets red cell production -anemia is typically normocytic, and Hb F and erythrocyte adenosine deaminase levels usually are normal -Red cell transfusion support is the mainstay of therapy if the child is symptomatic from anemia. Normalization of erythropoiesis occurs within weeks in the vast majority patients There may be a genetic predisposition to TEC in some families

fanconi anemia

-chromosome instability disorder characterized by aplastic anemia, physical abnormalities, and cancer susceptibility -1927, Dr. Guido Fanconi first described this syndrome in three brothers with skin pigmentation, short stature, and hypogonadism -is the most common of the inherited aplastic anemias

anemia of chronic kidney disease

-common complication of chronic kidney disease (CKD), with a positive correlation between anemia and renal disease severity -primary cause: inadequate renal production of erythropoietin -Without erythropoietin, the bone marrow lacks adequate stimulation to produce RBCs -uremia, which inhibits erythropoiesis and increases RBC fragility -patients experience chronic blood loss and iron deficiency from hemodialysis and frequent blood draws -Chronic inflammation and a restricted diet may also limit the iron available for erythropoiesis -anemia: normocytic and normochromic with reticulocytopenia -Burr cells are common peripheral blood film findings in cases complicated by uremia -can lead to cardiovascular complications, kidney failure, and suboptimal quality of life. -Kidney Disease Outcomes Quality Initiative of the National Kidney Foundation recommends annual hemoglobin testing in patients with CKD and investigation of the anemia if the hemoglobin is less than 13.5 g/dL in adult men and less than 12 g/dL in adult women -Treatment includes recombinant human erythropoietin or other erythropoiesis-stimulating agents (ESAs), with a goal hemoglobin range of 11 g/dL to 12 g/dL -Maintaining the hemoglobin above 13 g/dL is not recommended because of the increased risk of cardiovascular and thromboembolic complications -successfyl ESA therapy requires: adequate iron stores, so plasma ferritin level and percent transferrin saturation should also be monitored -Iron is administered with ESA therapy to maintain the transferrin saturation above 20% and the plasma ferritin level above 100 ng/mL for non-dialysis-dependent patients and above 200 ng/mL for hemodialysis-dependent patients -Iron therapy is not routinely recommended for ferritin levels above 500 ng/mL -Patients may become hyporesponsive to ESA therapy because of functional iron deficiency (FID) -FID, the bone marrow is unable to release iron rapidly enough to accommodate the accelerated erythropoiesis -transferrin saturation remains below 20%, but the serum ferritin level is normal or increased, indicating adequate iron stores -Patients with FID are unable to reach or maintain the target hemoglobin, even with high ESA doses -patients are able to reach the target hemoglobin after intravenous iron therapy -FID in CKD: decreased reticulocyte hemoglobin content, increased soluble transferrin receptor, and greater than 10% hypochromic RBCs in the peripheral blood -Other causes of ESA hyporesponsiveness include chronic inflammatory disease, infection, malignancy, aplastic anemia, antibody-mediated pure red cell aplasia, thalassemia, multiple myeloma, and the presence of hemoglobin H or hemoglobin S variants

Schwachman-Bodian-Diamond Syndrome clinical findings

-peripheral blood cytopenia and decreased pancreatic enzyme secretion -pancreatic insufficiency causes gastrointestinal malabsorption, which typically presents in early infancy -Patients have neutropenia and immune dysfunction and are at increased risk of severe infections and sepsis -patients have delayed bone maturation, and approximately 50% have failure to thrive and short stature

congenital pure red cell aplasia: diamond-blackfan anemia

-congenital erythroid hypoplastic disorder of early infancy with an estimated incidence of 7 to 10 cases per million live births -mutations in 9 genes: that encode structural ribosome proteins: RPS7, RPS10, RPS17, RPS19, RPS24, and RPS26 in the 40S subunit and RPL5, RPL11, and RPL35A in the 60S subunit -25% of patients have a mutation in the RPS19 gene, and mutations in the other eight genes account for another 25% of cases -Mutations in these ribosomal proteins disrupt ribosome biogenesis in DBA, but the pathophysiologic mechanisms leading to the clinical manifestations are currently unknown -Nearly 50% of DBA cases are linked to an autosomal dominant inheritance pattern, but sporadic mutations have also been reported -90% of patients show signs of the disorder during the first year of life, with a median age of 8 weeks; however, some patients with DBA are asymptomatic until adulthood -Approximately half of patients have characteristic physical anomalies, including craniofacial dysmorphisms, short stature, and neck and thumb malformations -characteristic peripheral blood finding is a severe macrocytic anemia with reticulocytopenia -WBC count is normal or slightly decreased, and the platelet count is normal or slightly increased -Bone marrow examination distinguishes DBA from the hypocellular marrow in aplastic anemia, because there is normal cellularity of myeloid cells and megakaryocytes and hypoplasia of erythroid cells -karyotype in DBA is normal. In most cases, Hb F and erythrocyte adenosine deaminase are increased; these findings distinguish DBA from TEC, in which these levels are normal -Therapy includes RBC transfusions and corticosteroids -50% to 75% of patients respond to corticosteroid therapy, side effects are severe with long-term use, including immunosuppression and growth delay -Bone marrow transplantation improves outcomes, with greater than 90% overall survival in patients younger than 10 years old transplanted with a matched-related donor, and 80% in those with a matched unrelated donor

IST

-consisting of antithymocyte globulin and cyclosporine, is used for patients older than 40 years of age and for patients without an HLAidentical sibling -Antithymocyte globulin decreases the number of activated T cells, and cyclosporine inhibits T-cell function, thereby suppressing the autoimmune reaction against the stem cells -two thirds of patients initially respond to IST; unfortunately, 30% to 40% relapse -outcomes in the IST-treated patients include a 10-year risk of developing hemolytic or thrombotic PNH and a 10% to 20% risk of myelodysplastic syndrome (MDS) or leukemia.

myelophthisic anemia

-due to the infiltration of abnormal cells into the bone marrow and subsequent destruction and replacement of normal hematopoietic cells -Metastatic solid tumor cells (particularly from lung, breast, and prostate), leukemic cells, fibroblasts, and inflammatory cells (found in miliary tuberculosis and fungal infections) -Cytopenia results from the release of substances such as cytokines and growth factors that suppress hematopoiesis and destroy stem, progenitor, and stromal cells -disruption of normal bone marrow architecture by the infiltrating cells, the marrow releases immature hematopoietic cells -unfavorable bone marrow environment, stem and progenitor cells migrate to the spleen and liver and establish extramedullary hematopoietic sites -unfavorable bone marrow environment, stem and progenitor cells migrate to the spleen and liver and establish extramedullary hematopoietic sites -severity of anemia is mild to moderate, with normocytic erythrocytes and reticulocytopenia -Peripheral blood findings include teardrop erythrocytes and nucleated RBCs, as well as immature myeloid cells and megakaryocyte fragments -infiltrating abnormal cells are detected in a bone marrow aspirate or biopsy specimen

biopsy of BM in aplastic anemia

-have prominent fat cells with areas of patchy marrow cellularity -required for accurate quantitative assessment of marrow cellularity, and severe hypocellularity is a characteristic feature of aplastic anemia -Erythroid, granulocytic, and megakaryocytic cells are decreased or absent -Dyserythropoiesis may be present, but there is typically no dysplasia of the granulocyte or platelet cell lines. -Blasts and other abnormal cell infiltrates are characteristically absent. -Reticulin staining is usually normal

CDA I

-inherited in an autosomal recessive pattern and is characterized by a mild to severe chronic anemia -caused by mutations in the CDAN1 gene on chromosome 15, which encodes codanin-1, a cell-cycle regulated nuclear protein. -exact role of codanin-1 in the pathophysiology of CDA I is unknown -Malformations of fingers or toes, brown skin pigmentation, and neurologic defects are found more frequently in CDA I than in the other CDA types -HGB: 6.5 g/dL to 11.5 g/dL, with a mean of 9.5 g/dL -RBCs are macrocytic and may exhibit marked poikilocytosis, basophilic stippling, and Cabot rings. -The erythroblasts are megaloblastoid and characteristically have internuclear chromatin bridges or nuclear stranding -are less than 5% binucleated erythroblasts. -The characteristic feature of the CDA I erythroblast is a spongy heterochromatin with a "Swiss cheese" appearance -treatment: includes interferon-a and iron chelation

PNH

-is characterized by an acquired stem cell mutation resulting in lack of the glycosylphosphatidylinositol (GPI)-linked proteins CD55 and CD59 -absence of CD55 and CD59 on the surface of the RBCs renders them more susceptible to complement-mediated cell lysis -important to test for PNH in acquired aplastic anemia because of the increased risk of hemolytic and/or thrombotic complications -diagnosis depended on the Ham acid hemolysis test: patients' cells were placed in acidified serum, and a positive result demonstrated lysis of RBCs. However, this test was poorly sensitive, because complement-mediated hemolysis was detected only in the presence of large numbers of circulating PNH cells -flow cytometric analysis for CD59 on RBCs and CD24 and CD14 on granulocytes and monocytes is used as a more sensitive diagnostic method and has replaced the Ham test in nearly all laboratories

alternative diagnosis

-lymphoma, myelofibrosis, and mycobacterial infections, which also may present with pancytopenia -these diagnoses often can be distinguished with a careful history, physical exam, and laboratory testing -Review of a peripheral blood film by an experienced morphologist is important -bone marrow evaluation and molecular testing for chromosome abnormalities and gene mutations can further distinguish these diagnoses -Anorexia nervosa also may present with pancytopenia. In these cases, the bone marrow is hypocellular and has a decreased number of fat cells -cytopenias revert with correction of the underlying disease

CDA II

-most common subtype and is inherited in an autosomal recessive pattern -results from mutations in the SEC23B gene on chromosome 20 -SEC23B encodes a component of the coat protein complex (COPII) that forms vesicles for transport of secretory proteins from the endoplasmic reticulum to the Golgi apparatus -pathophysiology is unknown -mild to moderate, with hemoglobins ranging from 9 g/dL to 12 g/dL and a mean hemoglobin of 11 g/dL -peripheral blood film, RBCs are normocytic with anisocytosis, poikilocytosis, and basophilic stippling -bone marrow has normoblastic erythropoiesis, with 10% to 35% binucleated forms and rare multinucleated forms -pseudo-Gaucher cells are also evident -Circulating RBCs hemolyze with the Ham acidified serum test but not with the sucrose hemolysis test -also known as HEMPAS (heriditary erythroblastic multinuclearity with positive acidified serum) -Ham test is no longer routinely used for CDA II confirmation, given the difficulty of appropriate quality control and the relative lack of testing availability in most laboratories -RBCs also agglutinate with anti antisera and show abnormal migration of band 3 using sodium dodecyl sulfate polyacrylamide gel electrophoresis -Treatment includes splenectomy and iron chelation: least common of the CDA subtypes, with about 60 cases reported in the literature, the majority being from one Swedish family -familial autosomal dominant form is associated with mutations in the KIF23 gene, which codes for a protein involved in cytokinesis -nonfamilial or sporadic form is extremely rare, with fewer than 20 cases reported -anemia is mild, and the hemoglobin is usually in the range of 8 to 14 g/dL, with a mean of 12 g/dL -RBCs are macrocytic, and poikilocytosis and basophilic stippling are evident. - The bone marrow has megaloblastic changes, and giant erythroblasts with up to 12 nuclei are a characteristic feature. Patients rarely require RBC transfusions, and iron overload is not observed

SBDS lab findings

-neutropenia less than 1.5 x 10^9 neutrophils -Half of the patients also develop anemia or thrombocytopenia, and one fourth develop pancytopenia -RBCs are usually normocytic but can be macrocytic, and approximately two thirds of patients have elevated Hb F -BM is hypocellular but can be normal or even hypercellular -Due to the pancreatic insufficiency, 72-hour fecal fat testing shows increased fat excretion, and serum trypsinogen and isoamylase levels are decreased compared with age-related reference intervals -comparison to cystic fibrosis, which can have a similar malabsorption presentation, patients with SBDS have normal sweat chloride tests. Testing for the SBDS gene mutation is commercially available and should be done in suspected patients and their parents

test for idosynchratic reactions

-no available tests -genetic variations in immune response pathways or metabolic enzymes may play a role -approximately twofold higher incidence of HLA-DR2 and its major serologic split, HLA-DR15, in aplastic anemia patients compared to the general population, but the relationship of this finding to disease pathophysiology has not been elucidated -genetic polymorphisms in enzymes that metabolize benzene increase susceptibility to toxicity, even at low exposure levels *includes: polymorphisms in glutathione S-transferase (GST) enzymes (GSTT1 and GSTM1), myeloperoxidase, nicotinamide adenine dinucleotide phosphate (reduced form, NADPH), quinine oxidoreductase 1, and cytochrome oxidase P450 2E1 -deficiency in GST due to the GSTT1 null genotype is overrepresented in whites, Hispanics, and Asians with aplastic anemia, with a frequency of 30%, 28%, and 75%, respectively -White patients with aplastic anemia also have a higher frequency (22%) of the GSTM1/ GSTT1 null genotype than the general population *GST is important for metabolism and neutralization of chemical toxins, and deficiencies of this enzyme may increase the risk of aplastic anemia

SBDS treatment prognosis

-no treatment is sometimes required -treatment consists of G-CSF for neutropenia, transfusion support for anemia and thrombocytopenia, and enzyme replacement for pancreatic insufficiency -risk of AML and MDS is approximately 19% at 20 years and 36% at 30 years -Allogeneic bone marrow transplantation is recommended in cases of severe pancytopenia, AML, or MDS -despite supportive care and attempted curative therapy, 5-year overall survival is 60% to 65%, with many deaths occurring from severe infections and malignancy -poor outcomes: HSCT occur due to graft failure, transplant-related toxicities, and recurrent leukemia

Pure Red Cell Aplasia (PRCA)

-rare disorder of erythropoiesis characterized by a selective and severe decrease in erythrocyte precursors in an otherwise normal bone marrow -Patients have severe anemia (usually normocytic), reticulocytopenia, and normal WBC and platelet counts -may be acquired or congenital, they have different therapeutic approaches

acquired aplastic anemia occurs in?

-occasionally as a complication of infection with Epstein-Barr virus, human immunodeficiency virus (HIV), hepatitis virus, and human parvovirus B19 -history of acute non-A, non-B, or non-C hepatitis 1 to 3 months before the onset of pancytopenia is found in 2% to 10% of patients with acquired aplastic anemia. may be mediated by such mechanisms as interferon gamma and cytokine release -associated with pregnancy is a rare occurrence, with fewer than 100 cases reported in the literature -10% of individuals with acquired aplastic anemia have a concomitant autoimmune disease and approximately 10% develop hemolytic or thrombotic manifestations of paroxysmal nocturnal hemoglobinuria (PNH)

telomeres in aplastic anemia

-one third of patients with acquired aplastic anemia have shortened telomeres in their peripheral blood granulocytes compared with age-matched controls -Telomeres protect the ends of chromosomes from damage and erosion, and cells with abnormally short telomeres undergo proliferation arrest and premature apoptosis -Telomerase is an enzyme complex that repairs and maintains the telomeres. Approximately 10% of patients with acquired aplastic anemia and shortened telomeres have a mutation in the telomerase complex gene for either the ribonucleic acid (RNA) template (TERC) or the reverse transcriptase (TERT) -cause for shortened telomeres in the other 90% of patients may be due to stress hematopoiesis or other yet unidentified mutations -stress hematopoiesis, there is an increase in progenitor cell turnover, and the telomeres become shorter with each cell division

second course of IST

-or an HSCT from an HLA-matched unrelated donor is an option, but survival is not as high as with HSCT from an HLA-identical sibling -response rate for a second course of IST is approximately 65% for those who experienced relapse and 30% for those whose disorder was initially refractive to IST -Individuals with PNH cells (CD55- CD59-) are almost twice as likely to respond to IST than are those who lack these cells. -the presence of both PNH cells and HLA-DR2 increases the likelihood of response by 3.5-fold -Granulocyte colony-stimulating factor (G-CSF), other hematopoietic growth factors, and steroids do not increase overall survival or improve the response rate; therefore, they are not recommended for routine use

aplastic anemia lab findings

-pancytopenia -only one or two cell lines may be decreased -absolute neutrophil count is decreased, and the absolute lymphocyte count may be normal or decreased -hemoglobin is usually less than 10 g/dL, the mean cell volume (MCV) is increased or normal, and the percent and absolute reticulocyte counts are decreased -Neutrophils, monocytes, and platelets are decreased in the peripheral blood, and the red blood cells are macrocytic or normocytic -Toxic granulation may be observed in the neutrophils, but the RBCs and platelets are usually normal in appearance -leukemic blasts and immature RBC are absent -serum iron level and percent transferrin saturation are increased, which reflects decreased iron use for erythropoiesis. -Liver function test results may be abnormal in cases of hepatitis-associated aplastic anemia -two thirds of patients have small numbers (less than 25%) of PNH clones in the peripheral blood but only 10% of patients develop a sufficient number of PNH cells to have the clinical and biochemical manifestations of PNH disease

aplastic anemia

-pancytopenia, reticulocytopenia, bone marrow hypocellularity, and depletion of hematopoietic stem cells -Approximately 80% to 85% of aplastic anemia cases are acquired, whereas 15% to 20% are inherited

fanconi lab findings

-pancytopenia, reticulocytopenia, and a hypocellular bone marrow -Macrocytic RBCs are often the first detected abnormality, and thrombocytopenia usually precedes the development of the other cytopenias -Fetal hemoglobin (Hb F) may be strikingly elevated, and a-fetoprotein is also increased -Chromosomal breakage analysis is the diagnostic test for Fanconi anemia -Patients' peripheral blood lymphocytes are cultured with the DNA cross-linking agents diepoxybutane (DEB) or mitomycin C (MMC) -Compared to normal lymphocytes, FA cells have a greater number of characteristic chromosome breaks and ring chromosomes, indicating increased fragility -Caution must be made in interpreting peripheral blood results, because they may be negative in the 10% to 15% of FA patients who have somatic mosaicism due to a reversion of one abnormal allele to the normal type -To confirm the diagnosis in these cases, chromosome breakage studies can be performed on cultured skin fibroblasts from a skin biopsy specimen

autoimmune pathophysiology in aplastic anemia

-patients undergoing pretransplant immunosuppressive conditioning had an improvement in cell counts (1) elevated blood and bone marrow cytotoxic (CD81) T lymphocytes with an oligoclonal expansion of specific T-cell clones (2) increased T cell production of such cytokines as interferon- g (IFN-g) and tumor necrosis factor-a (TNF-a), which inhibit hematopoiesis and induce apoptosis (3) upregulation of T-bet, a transcription factor that binds to the promoter of the IFN-g gene (4) increased TNF-a receptors on CD341 cells31; and (5) improvement in cytopenias after immunosuppressive therapy (IST) -two thirds of patients with acquired aplastic anemia respond to IST -nonresponders may have a severely depleted stem cell compartment or other pathophysiologic factors contributing to their cytopenias

Patients with inherited aplastic anemia may be misdiagnosed with acquired aplastic anemia if?

-symptoms manifest in late adolescence or adulthood or if the patients lack the typical clinical and physical characteristics of an inherited marrow failure syndrome (e.g., abnormal thumbs, short stature)

patients receiving immunosupressive therapy

-the risk of developing an abnormal karyotype is 14% at 5 years and 20% at 10 years

hematopoietic stem cell transplantation (HSCT) treatment for aplastic anemia

-treatment of choice for patients with severe aplastic anemia who are younger than 40 years of age and have a human leukocyte antigen (HLA)- identical sibling -only 20-30% meet these criteria

pancytopenia

decreased numbers of circulating red blood cells (RBCs),white blood cells (WBCs), and platelets *seen in most cases of BM failure, in severe or advantage -patients may be asymptomatic, can be detected during a routine blood examination -Sustained neutropenia increases the risk of life-threatening bacterial or fungal infections

severe depletion of hematopoietic stem and progenitor cells from the BM can be due to?

direct damage to stem cells, immune damage to stem cells, or other unknown mechanisms -direct damage to stem and progenitor cells results from DNA injury following exposure to cytotoxic drugs, chemicals, radiation, or viruses -Immune damage to stem cells results from exposure to drugs, chemicals, viruses, or other agents that cause an autoimmune cytotoxic T-lymphocytic destruction of stem and progenitor cells -