Bladder Melanosis: A rare case report

Introduction: Bladder melanosis is an extremely rare condition first reported in 1986 and refers to abnormal deposits of melanin in the urothelial bladder cells. Typically, it is considered a benign condition, but it has also been described associated with urothelial carcinoma and melanoma. Its diagnosis may be difficult for most urologists because of its rarity. Case Report: We present the case of a 64-year-old male, former smoker and with a history of previous transurethral resection of prostate with macroscopic hematuria and lower urinary tract symptoms over the last six months. Bladder cytology showed reactive transitional cells, with lots of histiocytes, containing a brown-blackish pigment, positive for Masson-Fontana technique. The patient was submitted to a transurethral resection (TUR) of bladder of all macroscopic lesions under general anesthesia because of the clinic suspicion. Bladder biopsy histologically revealed diffuse dark brown-black pigment mostly within the superficial lamina propria. In conclusion, the histopathological result was compatible with primary bladder melanosis. Our patient had a two-year follow-up with annual cystoscopy and cytology, with no signs of recurrence of lesions with normal macroscopic urothelium findings. Conclusion: Bladder melanosis of the urinary bladder is a rare condition. Initial evaluation should include cystoscopy and, eventually, upper urinary imaging. The possibility that bladder melanosis can be associated with premalignant and malignant urothelial lesions, suggests a close follow-up with, at least, annual cystoscopy and cytology. In our case, cytology had a pivotal role in the early diagnosis and characterization of the disease.