Pure red cell aplasia

Overview

Description: normocytic, normochromic anemia characterized by a severe reduction in circulating reticulocytes and marked reduction or absence of erythroid precursors in the bone marrow
Pathophysiology: thought to be related to abnormal T-cell function and IgG antibodies that target erythroblasts and erythropoietin
- Etiology
  - Acquired
    - Most often idiopathic
    - Possible associated conditions
      - Thymoma
      - Myelodysplastic syndrome
      - Adverse drugs effects (e.g., from phenytoin, chloramphenicol)
      - Parvovirus B19 infection
      - Autoimmune disorders (e.g., type 1 diabetes, thyroiditis, rheumatoid arthritis)
  - Congenital: Diamond-Blackfan anemia (DBA): see below
Diagnostics
- Low reticulocyte count
- Bone marrow biopsy shows marked reduction or absence of erythroid precursors.
Treatment
- Treatment of the underlying cause (e.g., cessation of possible offending agents, thymectomy)
- Red blood cell transfusion for symptomatic patients
- Immunosuppressive and/or cytotoxic agents (e.g., glucocorticoids, cyclosporine, cyclophosphamide)

Description
- Intrinsic defect of erythroid progenitor cells → ↑ apoptosis
- Usually autosomal dominant inheritance or associated with impaired ribosome synthesis mutations
- Rapid onset of macrocytic (nonmegaloblastic) anemia in infancy (usually diagnosed within the first year of life)
Additional clinical features: physical abnormalities manifest in ∼50% of affected individuals
- Fatigue, poor feeding
- Short stature, webbed neck
- Upper extremity malformations (e.g., triphalangeal thumbs)
- Microcephaly, micrognathia
- Hypertelorism, flat nasal bridge, cleft palate
- Congenital cataracts or glaucoma
- Atrial and ventricular septal defects
Diagnostics
- Electrophoresis
  - Elevated HbF levels
  - Low total Hb levels
- Specific laboratory findings
  - Elevated erythrocyte adenosine deaminase levels (eADA)
  - Increased expression of i antigen in RBCs