Xanthoma of the bladder.

We report a case of xanthoma of the bladder incidentally discovered during transurethral ureteral lithotripsy for a right ureteral stone and histopathologically diagnosed by cold cup biopsy. Xanthoma, a disorder of the lipid metabolism without tumorous or inflammatory changes, is rare in the bladder with only 7 cases reported previously. Interestingly, 5 of these 7 cases were reported in the Japanese literature, as were cases of xanthogranulomatous cystitis. We have no explanation for this occurrence. Xanthoma, caused by macrophages with the ability to phagocytose, is a benign lesion. It is necessary to continue careful followup by cystoscopy to determine if xanthoma increases or decreases in size.