Metastasis of malignant melanoma to urinary tract: a case report

Metastasis of malignant melanoma to urinary tract is reported to be rare. According to retrospective analysis of a single center study, improvement of overall survival was observed in patients with metastasis to the gastrointestinal tract that had undergone metastasectomy with curative intent. However, there is no significant evidence regarding resection for metastasis to urinary tract.

Case 1: an 86-year-old Japanese man was diagnosed with a small bladder tumor by computed tomography scan during post operative follow-up of malignant melanoma in the choroid of the left eye. Cystoscopy revealed black, nonpapillary tumors, suggesting metastatic malignant melanoma. Because no apparent invasive growth to muscle layer was observed by magnetic resonance imaging, transurethral resection was performed. Pathological appearance was compatible with metastatic malignant melanoma. No recurrence in urinary tract was observed; however, multiple liver metastasis was diagnosed at 3 months after surgery. Case 2: a 57-year-old Japanese man was diagnosed with right hydronephrosis due to ureteral tumor. He had a past history of subungual malignant melanoma to the left thumb 2 years prior to his visit. Right nephroureterectomy was performed, and pathological evaluation revealed metastatic malignant melanoma. He revisited 2 years later due to dysuria, and a large bladder tumor was revealed by ultrasound. Cystoscopy showed black-colored nonpapillary tumor, suggesting malignant melanoma. Total cystectomy was recommended; however, the patient withheld consent. Therefore, we performed transurethral resection. The resulting pathological finding was compatible with metastatic malignant melanoma without invasion to muscle layer. He remained free from local recurrence and metastasis for 22 years after surgery.

We successfully performed metastasectomy for bladder and ureteral metastases without recurrence in the urinary tract. Long recurrence-free survival was observed in case 2. Complete resection for metastasis of malignant melanoma may have the potential to improve survival.