Plasmablastic lymphoma (PL) is an uncommon B-cell lymphoma that is strongly associated with human immunodeficiency virus (HIV) infection, and displays distinctive affinity for extranodal presentation in the oral cavity. We report the case of a PL involving the stomach in a 36 year-old man HIV+ patient, associated with Kaposi sarcoma (KS) in sections adjacent to lymphoma. He had a positive history of Castleman disease and KS in a lymphoid node biopsy.