A 46-year-old man with HIV, not on HAART (highly active anti-retroviral therapy), presented with abdominal pain and urinary retention. A large, suprapubic mass and inguinal lymphadenopathy was palpated on examination. Laboratory data showed renal failure, hyperuricemia, anemia, and thrombocytopenia. CT scans showed bilateral hydronephrosis caused by a pelvic mass involving the bladder with caudal extension encasing the ureters bilaterally. There was diffuse retroperitonal, abdominal, and pelvic lymphadenopathy. Fine needle aspirations of the inguinal nodes and pelvic mass were nondiagnostic. Wright-Giemsa stain of a urine cytospin specimen (panel A) showed large atypical cells with high nuclear:cytoplasmic ratio. The cells were negative for CD19, CD20, and CD79a on flow cytometry. Human herpesvirus-8 (HHV-8; panel B) and EBV stains on the inguinal lymph node were positive. A diagnosis of extracavitary primary effusion lymphoma (PEL) was made. PEL is an HHV-8–associated illness seen in