(See also Overview of Decreased Erythropoiesis.)
Congenital pure red cell aplasia (Diamond-Blackfan anemia) is discussed elsewhere.
Etiology
Pure red blood cell (RBC) aplasia is most often due to an inappropriate immune response causing suppression of erythropoiesis. Well-known causes include
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Thymomas
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Drugs (eg, tranquilizers, antiseizure drugs)
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Toxins (organic phosphates)
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Riboflavin deficiency
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Pregnancy
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HIV infection
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Lymphoproliferative diseases (chronic lymphocytic leukemia, large granular lymphocyte leukemia, chronic myeloid leukemia, Hodgkins lymphoma, non-Hodgkins lymphoma, multiple myeloma)
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ABO-mismatched bone marrow transplant
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Autoimmune disorders
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Collagen vascular diseases
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Solid tumors
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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)
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Myelodysplastic syndrome (MDS)
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
Pure RBC aplasia presents with a normocytic anemia but normal white blood cell 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. If possible, a marrow burst forming units-erythroid (BFU-E) assay should be obtained to differentiate benign causes of pure red blood cell aplasia from MDS (1).
Chest CT is indicated to evaluate for thymoma in the absence of another identified cause.
Diagnosis reference
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1. DeZern AE, Pu J, McDevitt MA, et al: Burst-forming unit–erythroid assays to distinguish cellular bone marrow failure disorders. Exp Hematol 41:808–816, 2013.
Treatment
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.
Thymectomy is performed in patients with thymoma-associated pure RBC aplasia; most patients improve but are not always cured.
Key Points
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Pure red cell aplasia involves isolated erythroid hypoplasia.
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Immune-mediated suppression of the erythroid cell line is the most likely cause.
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Bone marrow cellularity is normal with an arrest of erythroid maturation causing a normocytic anemia.
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Direct treatment of underlying cause with thymectomy, IV immune globulin (IVIG), or immunosuppression.
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