We report a case of recurrent body cavity-based non-Hodgkin's lymphoma in a patient with advanced acquired immunodeficiency syndrome who presented with bilateral pleural effusions, without evidence of an associated tumor mass. The lymphoma cells were large and pleomorphic, lacking pan-T- and pan-B-cell markers, but expressing activation markers (CD30, CD38, and HLA-DR). The purpose of this article is to discuss the radiological-pathological correlation of body cavity-based lymphoma with a review of the entities that should be included in the differential diagnosis of patients with malignant pleural effusions.