AA presents with pancytopenia, and bone marrow biopsy will reveal hypocellularity. It can be caused most commonly by autoimmune processes, direct injury to the bone marrow (toxic effect, drugs, radiation, etc), viral infection, clonal disorders (eg, paroxysmal nocturnal hemoglobinuria, myelodysplastic syndrome, acute myeloid leukemia), or genetic disorders (eg, Fanconi anemia, Shwachman-Diamond syndrome, thrombopoietin abnormalities, telomere abnormalities). Despite the various pathophysiologic mechanisms that can lead to AA, the disorder remains rare, with an incidence in the Western world of 2 per million per year, with half of all cases occurring before the age of 30 years.
Patients with AA usually present with recurrent infections due to neutropenia, mucosal hemorrhage or menorrhagia due to thrombocytopenia, and fatigue, dyspnea, and cardiopulmonary compromise due to anemia.
D61.9 – Aplastic anemia, unspecified
306058006 – Aplastic Anemia
Differential Diagnosis & Pitfalls
- Megaloblastic anemia (deficiencies of vitamin B12 and/or folate)
- Bone marrow involvement by other clonal or infiltrative disorder (malignancies, large granular lymphocytic leukemia, primary myelofibrosis, among others)
- Predictable, cytotoxic effect of radiation or chemotherapy (see drug-induced anemia)
- Bone marrow infiltrative disorders (myelofibrosis, tuberculosis, fungal infection, certain neoplasms)
- Myeloid malignancies (acute myeloid leukemia, myelodysplastic syndromes)
- Sequestration (hypersplenism, cirrhosis)
- Severe sepsis
Drug Reaction Data