Acquired Amegakaryocytic Thrombocytopenia Misdiagnosed as Immune Thrombocytopenia: A Case Report

Abstract

Introduction: Acquired amegakaryocytic thrombocytopenia (AATP) is a rare bleeding disorder that causes severe thrombocytopenia with preserved hematopoiesis of other cell lineages. Many cases are misdiagnosed and treated as immune thrombocytopenia.

Case presentation: We report a case of AATP, in a 50-year-old man, that was treated as immune thrombocytopenia for years with no clinical response. The disorder later was diagnosed as AATP after bone marrow biopsy and was successfully treated with cyclosporine.

Discussion: The exact mechanism of AATP remains unclear; it is suspected to be an immune-mediated process. Patients with AATP present with severe bleeding and thrombocytopenia, which is usually unresponsive to high-dose corticosteroids. There are no standard treatment guidelines for AATP. Cyclosporine and antithymocyte globulin are found to be effective in some cases. The prompt diagnosis of AATP is vital because it carries high mortality because of excessive bleeding, and it can progress into aplastic anemia or myelodysplastic syndrome.

Figure 1.

Varying cellularity in the bone marrow of a man with a misdiagnosis of immune thrombocytopenia. (Compare these photomicrographs with Figure 2.) A. Bone marrow shows a region of 40% cellularity (×10). B. Higher magnification view (×20) of the same area showing a rare megakaryocyte in the bone marrow (arrow).

Figure 2.

Photomicrograph of a different part of the same patient’s bone marrow showing 0% cellularity (with no hematopoietic cells) but intact adipocyte framework (×10).

Figure 3.

Graph of timeline of platelet count (×10³/μL) response to cyclosporine therapy. BID = twice daily; CyA = cyclosporine; D = day.