Metastatic Malignant Melanoma to Urinary Bladder: A Potential Pitfall for High-Grade Urothelial Carcinoma.

We present a case of a 61-year-old female presenting with a bladder tumor that occurred 7 years after her previous diagnosis of Clark's level III mid-back melanoma. The bladder tumor was submitted to histopathology without accompanying clinical history, and an initial diagnosis of high-grade urothelial carcinoma was rendered based on epithelioid and sarcomatoid appearing pleomorphic histopathology. We present this case to highlight the diagnostic challenge presented by the rare occurrence of metastatic melanoma to the urinary bladder and the potential pitfall of this lesion being diagnosed as high-grade urothelial carcinoma in the presence of limited clinical history.

Urinary bladder adenocarcinoma arising in a spina bifida patient.

Urinary bladder adenocarcinomas are rare malignancies accounting for approximately 2.5% of all urothelial neoplasms. Intestinal metaplasia of the urothelium indicates the presence of intestinal-type goblet cells and was generally observed to coexist with or to precede the diagnosis of bladder adenocarcinomas.