Multiple myeloma presenting initially as a solitary pleural effusion later complicated by malignant plasmacytic ascites.

A pleural effusion is a rare presenting feature of multiple myeloma and can be a complication of myelomatous ascites as well. An additional unique feature of our case includes the finding of a normal bone marrow at the time of presentation despite the aggressive course of the disease. To the best of our knowledge after an extensive medical literature review, this case is the first one of multiple myeloma presenting with a plasmacytic pleural effusion, a negative bone marrow, and a late complication of plasmacytic ascites. Involvement of serous cavities in myeloma carries a poor prognosis, and there is currently no standard effective treatment regimen.