(See also Overview of Decreased Erythropoiesis Overview of Decreased Erythropoiesis Anemia, a decrease in the number of red blood cells (RBCs), hemoglobin (Hb) content, or hematocrit (Hct), can result from decreased RBC production (erythropoiesis), increased RBC destruction... read more .)
Congenital pure red cell aplasia ( Diamond-Blackfan anemia Perinatal Anemia Anemia is a reduction in red cell mass or hemoglobin and is usually defined as hemoglobin or hematocrit > 2 standard deviations below the mean for age. Some authorities also consider a relative... read more ) is discussed elsewhere.
Etiology of Pure Red Blood Cell Aplasia
Pure red blood cell (RBC) aplasia is most often due to an inappropriate immune response causing suppression of erythropoiesis. Well-known causes include
Collagen vascular diseases
Drugs (eg, tranquilizers, antiseizure drugs, recombinant erythropoietin)
Lymphoproliferative diseases ( chronic lymphocytic leukemia Chronic Lymphocytic Leukemia (CLL) Chronic lymphocytic leukemia (CLL) is characterized by progressive accumulation of phenotypically mature malignant B lymphocytes. Primary sites of disease include peripheral blood, bone marrow... read more , large granular lymphocyte leukemia, chronic myeloid leukemia Chronic Myeloid Leukemia (CML) Chronic myeloid leukemia (CML) occurs when a pluripotent stem cell undergoes malignant transformation and clonal myeloproliferation, leading to a striking overproduction of mature and immature... read more , Hodgkins lymphoma, non-Hodgkins lymphoma, multiple myeloma)
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)
Toxins (organic phosphates)
Symptoms of Pure Red Blood Cell Aplasia
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 of Pure Red Blood Cell Aplasia
Complete blood count (CBC), reticulocyte count
Bone marrow examination
Pure RBC aplasia manifests 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 autoimmune causes of pure red cell aplasia from primary bone marrow disorders such as myelodysplastic syndrome Myelodysplastic Syndrome (MDS) The myelodysplastic syndrome (MDS) is group of clonal hematopoietic stem cell disorders typified by peripheral cytopenia, dysplastic hematopoietic progenitors, a hypercellular or hypocellular... read more ( 1 Diagnosis reference 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... read more ).
Chest CT is indicated to evaluate for thymoma in the absence of another identified cause.
Treatment of Pure Red Blood Cell Aplasia
Sometimes intravenous immunoglobulin (IVIG) or thymectomy
Pure RBC aplasia has been successfully managed with immunosuppressants (eg, prednisone, cyclosporine, or cyclophosphamide), especially when an autoimmune mechanism is suspected
Pure RBC aplasia secondary to parvovirus infection is treated with intravenous immune globulin.
Thymectomy is done in patients with thymoma-associated pure RBC aplasia; most patients improve but are not always cured.
Pure red cell aplasia involves isolated 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.