Macrocytic anemia and thrombocytosis associated with thymoma: a case report

Thymomas are often associated with autoimmune disorders. We report on a 45-year-old female patient with thymoma and hypogammaglobulinemia (Good's syndrome) who developed symptomatic macrocytic anemia (Hb 4.4 g/dl, MCV 112 fl) and thrombocytosis (Plt 442 G/l). Besides hypogammaglobulinemia (IgG 589 mg/dl), an inverted ratio of CD4(+)/CD8(+) cells was seen. The bone marrow biopsy showed a slightly hypercellular bone marrow with normal granulopoiesis, normal megakaryopoiesis and a mild dyserythropoiesis without any ring-sideroblasts. The in-vitro stem cell culture from the bone marrow revealed an atypical growth of macroclusters, reduced BFU-E and CFU-GEMM colony growth, whereas the CFU-GM colony growth was within the normal range. The chromosomal analysis showed a normal karyotype. The plasma vitamin B(12) and folate levels were within normal ranges, and we could not detect any autoantibodies. These findings excluded the differential diagnoses pure red cell aplasia (PRCA) and pernicious anemia. After resection of the thymoma of mixed cell type, the macrocytic anemia and thrombocytosis disappeared. The clinical course was complicated by a cerebral palsy and a life-threatening fungal septicemia after surgery. In the third year after thymectomy, hyporegenerative macrocytic anemia and thrombocytosis reappeared and an immunosuppressive treatment with prednisolone (1 mg/kg BW) was started. After initiation of the prednisolone therapy, reticulocyte counts increased and macrocytic anemia as well as thrombocytosis disappeared. The normalization of these laboratory parameters during glucocorticoid therapy suggests that in rare cases the constellation of macrocytic anemia, thrombocytosis and hypogammaglobulinemia may be due to an underlying immunologic mechanism.