Primary malignant melanoma of the male urethra: a case report.

We present a rare case of a 69-year-old male patient with serendipitous urethral melanoma. He complained of dysuria and recurrent urinary retention and was initially diagnosed with benign prostatic hyperplasia. Accidentally, a dark-brown pigmented macula was found in the distal urethra at the end of transurethral prostatectomy when we exited the resectoscope, transurethral resection of the nidus and sent to pathological examination showed the characteristics of melanoma. No other lesions were found on further examination and the patient preferred a close follow-up cystoscopy rather than an immediate urethrectomy. Unsurprisingly, he relapsed in the urethra with the local disease three months later and we treated him with partial urethrectomy, followed by watchful waiting for 11 months. However, the patient was readmitted for hematuria, and 18F-FDG PET-CT showed a large number of pelvic and bone metastatic lesions. Therefore, eight cycles of single-agent dacarbazine chemotherapy were administered, and the disease was demonstrated prolonged stabilization. Follow-up was conducted every 3 months, during which time palliative transurethral resection of the melanoma in the bladder was performed to control urinary tract infections. Although the prognosis of the disease is extremely poor, this patient has gained more than 50 months of overall survival and is alive to date.