Pelvic lipomatosis is a rare, proliferative disease involving an overgrowth of normal fat in the pelvic retroperitoneal space. Cystitis glandularis, cystitis cystica, or cystitis follicularis can be observed in 75% of patients with pelvic lipomatosis. We describe a 58-yr-old man with pelvic lipomatosis in whom adenocarcinoma of the bladder was diagnosed in the second transurethral resection of the bladder 1 month after the first operation. This proliferative disease can cause obstruction of the bladder drainage leading to a proliferative cystitis because of an altered environment rich in protein fluid. Because the association of this proliferative disease with adenocarcinoma of the bladder is frequent, we recommend close follow-up of these patients to detect the associated adenocarcinoma of the bladder. (C) 2004 Elsevier Inc. All rights reserved.