Aplastic Anemia: Etiology, Presentation, Diagnosis, and Treatment Strategies

Aplastic anemia (AA) is defined by pancytopenia with a hypocellular bone marrow (<25% cellularity, or 25–50% with <30% hematopoietic cells).

Etiology

• Acquired (most common): Idiopathic (immune-mediated), drugs (chloramphenicol, carbamazepine, gold), toxins (benzene, pesticides), radiation, viruses (hepatitis, EBV, parvovirus B19, HIV), pregnancy.
• Inherited: Fanconi anemia, dyskeratosis congenita, Shwachman-Diamond syndrome, Diamond-Blackfan anemia.

Clinical Presentation

• Anemia: Fatigue, pallor, dyspnea on exertion.
• Neutropenia: Recurrent or severe infections.
• Thrombocytopenia: Petechiae, ecchymoses, mucosal bleeding.

Diagnosis

• CBC showing pancytopenia with low reticulocyte count.
• Bone marrow biopsy: hypocellularity with fatty replacement, no abnormal infiltrates.
• Cytogenetics and gene panel for inherited forms.

Treatment

• Severe/very severe AA (age <40, matched donor): Allogeneic hematopoietic cell transplantation (HCT) is curative.
• Others: Immunosuppressive therapy (IST): horse anti-thymocyte globulin (ATG) + cyclosporine (+ eltrombopag). Response rate ~60–70%.
• Supportive care: Leukoreduced, irradiated transfusions; growth factors (G-CSF, eltrombopag); antimicrobial prophylaxis.

Long-term monitoring for clonal evolution (MDS, AML) is essential regardless of initial treatment.