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Pure Red Blood Cell Aplasia

By Evan M. Braunstein, MD, PhD, Assistant Professor of Medicine, Division of Hematology, Department of Medicine, Johns Hopkins School of Medicine

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Acquired pure red blood cell aplasia is a disorder of erythroid precursors that results in an isolated normocytic anemia. White blood cells and platelets are not affected. Symptoms result from anemia and include fatigue, lethargy, decreased exercise tolerance and pallor. Diagnosis requires demonstration of peripheral normocytic anemia and a normocellular bone marrow biopsy with absence of erythroid maturation. Treatment usually involves treatment of underlying cause and in some cases thymectomy or immunosuppression.

Congenital pure red cell aplasia (Diamond-Blackfan anemia) is discussed elsewhere.

Etiology

Pure RBC aplasia is most often due to an inappropriate immune response causing suppression of erythropoiesis. Well-known causes include

  • Thymomas

  • Drugs (eg, tranquilizers, anticonvulsants)

  • Toxins (organic phosphates)

  • Riboflavin deficiency

  • Pregnancy

  • HIV

  • Lymphoproliferative diseases (chronic lymphocytic leukemia or large granular lymphocyte leukemia)

  • ABO-mismatched bone marrow transplant

  • Parvovirus B19, particularly in immunocompromised patients such as those with HIV infection (the parvovirus binds to the blood group P antigen on erythroid precursors and is directly cytotoxic to the cells)

Symptoms

Symptoms of pure RBC aplasia are generally mild and relate to the degree of the anemia or to the underlying disorder. The onset of pure red blood cell anemia usually is insidious, often occurring over weeks or months. Symptoms related to anemia include fatigue, lethargy, decreased exercise tolerance and pallor.

Diagnosis

  • CBC, reticulocyte count

  • Bone marrow examination

Pure RBC aplasia presents with a normocytic anemia but normal WBC and platelet counts. Reticulocytes are decreased. The bone marrow reveals normal cellularity with a maturation arrest at the proerythroblast stage. In parvovirus B19 infection, giant pronormoblasts may be present.

Treatment

  • Immunosuppression

  • Sometimes intravenous immunoglobulin (IV Ig) or thymectomy

Pure RBC aplasia has been successfully managed with immunosuppressants (prednisone, cyclosporine, or cyclophosphamide), especially when an autoimmune mechanism is suspected. Pure RBC aplasia secondary to parvovirus infection is treated with intravenous immunoglobulin. Because patients with thymoma-associated pure RBC aplasia improve after thymectomy but are not always cured, CT is used to seek the presence of such a lesion, and surgery is considered.

Key Points

    • Pure red cell aplasia involves pure erythroid hypoplasia.

    • Immune-mediated suppression of the erythroid cell line is the most likely cause.

    • Bone marrow cellularity is normal with an arrest of erythroid maturation causing a normocytic anemia.

    • Direct treatment of underlying cause with thymectomy, IV immune globulin (IVIG), or immunosuppression.

Drugs Mentioned In This Article

  • Drug Name
    Select Trade
  • NEORAL, SANDIMMUNE
  • RAYOS
  • CYTOXAN (LYOPHILIZED)