Extramedullary hematopoietic pleural effusion in Waldenström's macroglobulinemia

Extramedullary hematopoietic effusion (EHE) is one of the extremely rare phenomena associated with extramedullary hematopoiesis, which is caused by serous effusions, including pleural effusion, and may be related to hematologic disorders and neoplasms. Herein, we present the case of an 81‐year‐old man with EHE accompanying Waldenström's macroglobulinemia (WM). The patient complained of anemia and dyspnea. The chest X‐ray and computed tomography showed a massive left pleural effusion, and the aspirates revealed infiltration of the immature myeloid cells and megakaryocytes, in addition to the lymphoma cells. To our knowledge, this is the first report of EHE in WM.