A 35-year-old woman comes to the physician complaining of weakness, fatigue, and pallor. She denies heavy menses or melena. Physical examination is unremarkable except for conjunctival pallor. Laboratory results are as follows: Iron studies and serum B₁₂ and folic acid levels are within normal limits. Bone marrow biopsy shows absence of erythroid precursors but preserved myeloid and megakaryocytic elements. Further workup would most likely show which of the following?

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This patient's pallor and fatigue suggest that she is suffering from anemia, which is confirmed by her low erythrocyte count, low percentage of reticulocytes (decreased RBC production), and low hemoglobin. Importantly, her white blood cell and platelet counts are within normal limits and their bone marrow precursors appear normal as well. The most likely diagnosis is pure red cell aplasia (PRCA), a rare form of marrow failure characterized by severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis. The pathogenesis of PRCA often involves the inhibition of erythropoietic precursors and progenitors by IgG autoantibodies or cytotoxic T lymphocytes. It has been associated with immune system diseases such as thymomas and lymphocytic leukemias. When a thymoma is present, removal can occasionally cure PRCA. Thus, all patients with PRCA should undergo a chest CT scan. PRCA can also result from parvovirus B19 infection. This virus preferentially attacks and destroys proerythroblasts. Recent parvovirus infection can be confirmed via the detection of anti-B19 IgM antibodies in the serum. (Choice A) Hepatocellular carcinoma (HCC) can cause anemia of chronic disease, in which the total iron binding capacity is low. However, this patient's iron studies are within normal limits. HCC tumors may also secrete erythropoietin, although polycythemia is less common. (Choice B) Renal cell carcinoma (RCC) can cause both anemia of chronic disease and iron deficiency anemia due to chronic hematuria. Some renal cell tumors can produce erythropoietin and cause polycythemia. Thus, anemia, polycythemia, or normal hemoglobin may be present in the setting of RCC. However, selective absence of erythroid precursors in the bone marrow would not occur with RCC. In addition, RCC is rare in younger patients, whereas benign thymomas are more common. (Choice D) Cerebellar hemangioblastomas can produce erythropoietin and are often associated with polycythemia. (Choice E) Uterine fibroids can cause bleeding and may result in microcytic hypochromic anemia with iron studies showing low iron and increased total iron binding capacity. However, fibroids can also produce erythropoietin and can cause polycythemia. Educational objective: Pure red cell aplasia is a rare form of marrow failure characterized by severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis. Pure red cell aplasia is associated with thymoma, lymphocytic leukemias, and parvovirus B19 infection.

A 35-Year-Old Woman Comes to the Physician Complaining of Weakness