Extramedullary hematopoietic pleural effusion accompanied by follicular lymphoma.

Extramedullary hematopoietic effusion (EHE) is recognized to be an unusual phenomenon accompanied by hematologic disorders. Only a few reports are available of EHE occurring in patients with lymphoma. We herein report the case of a 54-year-old man with follicular lymphoma. Bone marrow aspirates and biopsied specimens showed diffuse invasion of small cleaved atypical lymphoid cells that were positive for CD10, 20, bcl2, immunoglobulin lambda and Bcl-2-IgH rearrangement. The pleural effusion aspirates and a biopsied specimen obtained via thoracoscopy revealed megakaryocytes and immature myeloid cells in addition to lymphoma cells. To the best of our knowledge, this is the first report of EHE accompanied by lymphoma according to the World Health Organization classification.