Pure Red Cell Aplasia as an Isolated Paraneoplastic Manifestation of Thymoma: A Case Report and Literature Review.

Thymomas are epithelial tumors of the anterior mediastinum and are frequently associated with paraneoplastic autoimmune disorders. Pure red cell aplasia (PRCA) is a rare but clinically significant complication, caused by immune-mediated suppression of erythropoiesis. We report a case of a 52-year-old male with a previously diagnosed but untreated thymoma, who presented after 9 years with severe normocytic, normochromic anemia and reticulocytopenia. Bone marrow examination revealed selective erythroid suppression with preservation of myeloid and megakaryocytic lineages, consistent with PRCA. Imaging demonstrated a large anterior mediastinal mass measuring 16 cm. The patient received supportive blood transfusions followed by surgical thymectomy. Histopathological and immunohistochemical analysis confirmed a mixed spindle cell thymoma (Type A/AB). Postoperatively, the patient achieved complete hematological recovery without additional immunosuppressive therapy. This case highlights that thymoma-associated PRCA may present as an isolated paraneoplastic manifestation without neuromuscular symptoms. It underscores the crucial role of thymectomy in restoring erythropoiesis and achieving transfusion independence. To our knowledge, this is the first reported case of thymoma-associated PRCA in Syria, providing valuable insight for clinicians managing similar rare presentations.