37 Aplastic Anemia
Michelle To and Valentin Villatoro
Bone Marrow Failure:
Bone marrow failure is characterized by reduced hematopoiesis in the bone marrow resulting in cytopenias in one or more cell lines. Decreased hematopoiesis can be attributed to:1
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Destruction of hematopoietic stem cells due to acquired causes
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Destruction of hematopoietic stems cells due to inherited causes
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Ineffective erythropoiesis
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Disruption of bone marrow microenvironment
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Reduced production of growth factors and hormones related to hematopoiesis
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Infiltration of the bone marrow
Aplastic anemia is a bone marrow failure syndrome that is characterized by a decreased cell count in all cell lines (pancytopenia) and a hypocellular (aplastic) bone marrow. (McKenzie ch 16 pg 303, Rodak ch 22 pg 332) Unlike other anemias, hepatosplenomegaly and lymphadenopathy are absent. (McKenzie ch 16 pg 307)
Cause(s):
There is no known, single cause of aplastic anemia but it’s development can be associated with a variety of clinical states and agents which can be either acquired or inherited.1,2 It is thought that acquired causes of aplastic anemia can lead to an immunologic response against one’s own hematopoietic stem cells.1
Table 1. List of acquired and inherited causes of aplastic anemia.1-3
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Acquired: Idiopathic Drugs and Chemicals Radiation Infectious agents Clonal Disorders (e.g. MDS, PNH) |
Inherited: Fanconi Anemia (autosomal recessive, rare X-linked recessive) Dyskeratosis congenita Shwachman-Diamond Syndrome |
Laboratory Features of Aplastic Anemia:1,3
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CBC: RBC: Decreased WBC: Decreased PLT: Decreased Hb: Decreased RETIC: Decreased MCV: Normal to increased |
PBS: Pancytopenia (Thrombocytopenia, neutropenia, anemia) Normochromic Normocytic or macrocytic |
BM: Hypocellular or dry tap Fatty infiltration |
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Iron Studies: Serum Iron: Increased Ferritin: Increased Transferrin: Normal Transferrin Saturation: Normal to increased |
Other Tests: Molecular testing Flow cytometry |
References:
1. Lo C, Glader B, Sakamoto KM. Bone marrow failure. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 331-47.
2. Laudicina R. Hypoproliferative anemias. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 302-16.
3. Perkins SL. Aplastic anemia including pure red cell aplasia, congenital dyserythropoietic anemia, and paroxysmal nocturnal hemoglobinuria. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 156-75.
