Melanosis of the bladder: Case study of a rare and obscure entity

Melanosis of the bladder is a rare condition defined by the development of melanin in the bladder's urothelium and/or macrophages in the lamina propria. This condition first became known in humans in 1986, with fewer than 30 cases described in the English medical literature to date.

We present the rare case of bladder melanosis affecting an 85-year-old patient. It was suspected during a cystoscopy, which initially falsely suggested a flat bladder tumor. Following the resection, the histological diagnosis of melanosis was retained. The diagnosis is purely histological, which allows ruling out the main differential pathology, which is bladder melanoma, itself an extremely rare entity.

The clinical presentation varies greatly; however, it is uncertain whether this symptomatology is specific to this condition or relates to other pathologies in the lower urinary tract.

Although considered a benign pathology, several authors suggest surveillance by cystoscopy. In this article, we discuss the clinical significance as well as the possible follow-up of this rare entity.