Pure Red Cell Aplasia

Aregenerative anemia (PRCA). The unaffected lineages appear quantitatively and qualitatively normal. In all of the single-lineage failure syndromes (PRCA, pure white cell aplasia, amegakaryocytic thrombocytopenia), progression to pancytopenia or leukemia is unusual.

Classification

• Self-limited:
  Transient erythroblastopenia of childhood
  Transient aplastic crisis of hemolysis (acute B19 parvovirus infection)
• Fetal red blood cell aplasia:
  Nonimmune hydrops fetalis (in utero B19 parvovirus infection)
• Hereditary pure red cell aplasia:
  Congenital pure red cell aplasia (Diamond-Blackfan anemia)
• Acquired pure red cell aplasia:
  Cancer: Thymoma, Lymphoid malignancies, Paraneoplastic to solid tumors.
• Connective tissue disorders with immunologic abnormalities:
  Systemic lupus erythematosus, juvenile rheumatoid arthritis, rheumatoid arthritis
  Multiple endocrine gland insufficiency
• Viruses:
  Persistent B19 parvovirus, hepatitis, adult T cell leukemia virus, Epstein-Barr virus
• Pregnancy
• Drugs:
  Especially phenytoin, azathioprine, chloramphenicol, procainamide,isoniazid
• Antibodies to erythropoietin
• Idiopathic

Diagnosis

Anemia, reticulocytopenia, and absent or rare erythroid precursor cells in the bone marrow.

Diamond-Blackfan anemia (DBA)

It is congenital PRCA, and is diagnosed at birth or in early childhood and often responds to glucocorticoid treatment; mutations in ribosome protein genes are etiologic.

Clinical associations

PRCA has important associations with immune system diseases, large granular lymphocytosis or chronic lymphocytic leukemia.

Etiology

Antibodies to RBC precursors are frequently present in the blood, but T cell inhibition is probably the more common immune mechanism.

Persistent Parvovirus B19 infection

Chronic parvovirus infection is an important, treatable cause of PRCA. This common virus causes a benign exanthem of childhood (fifth disease) and a polyarthralgia/arthritis syndrome in adults. In normal individuals, acute infection is resolved by production of neutralizing antibodies to the virus, but in the setting of congenital, acquired, or iatrogenic immunodeficiency, persistent viral infection may occur. The bone marrow shows red cell aplasia and the presence of giant pronormoblasts, which is the cytopathic sign of B19 parvovirus infection. Viral tropism for human erythroid progenitor cells is due to its use of erythrocyte P antigen as a cellular receptor for entry.

Treatment

Red cell aplasia is compatible with long-term survival with supportive care alone: a combination of erythrocyte transfusions and iron chelation. For persistent B19 parvovirus infection, almost all patients respond to intravenous immunoglobulin therapy (e.g., 0.4 g/kg daily for 5 days), although relapse and retreatment may be expected, especially in patients with AIDS. Idiopathic PRCA respond favorably to mmunosuppression. Most first receive a course of glucocorticoids. Also effective are cyclosporine, ATG, azathioprine, and cyclophosphamide.