Acquired Amegakaryocytic Thrombocytopenia after Thymectomy in a Case of Pure Red Cell Aplasia Associated with Thymoma

The association of thymoma with pure red cell aplasia has been well documented, but amegakaryocytic thrombocytopenia is not a recognized paraneoplastic syndrome complicating thymoma. We report a case of thymoma-complicated pure red cell aplasia and amegakaryocytic thrombocytopenia in a 73-yr-old woman. Pure red cell aplasia was diagnosed seven months after the detection of thymoma. One year after the diagnosis of pure red cell aplasia and seven months after thymectomy, bone marrow aspiration and biopsy showed an absence of megakaryocytes, marked erythroid hypoplasia with normal myeloid series. A diagnosis of amegakaryocytic thrombocytopenia and pure red cell aplasia was made. Oral steroid maintenance therapy resulted in recovery of platelet count. She has still transfusion-dependant anemia but platelet and neutrophil counts had been maintained in normal range for more than five months, until the last follow-up. We think that autoreactive T cells may induce a clinical autoimmune response even after eradication of thymoma, and aplastic anemia as a late complication following thymectomy was described in previous cases. This patient also has to be under a close observation because of the possibility to evolve into aplastic anemia. (Korean J Lab Med 2010;30:244-8)