[Nested-variant urothelial carcinoma. Case report and molecular aspects].

The nested variant of urothelial carcinoma is a rare urothelial neoplasia which is characterized by relatively bland morphology and early muscle-invasive growth. We report on a 65-year-old male patient with a non-invasive high-grade urothelial lesion (carcinoma in situ and pTa G3). After treatment with BCG an invasive urothelial carcinoma was discovered whereas the carcinoma in situ had disappeared. Examination of the bladder specimen showed a nested-variant urothelial carcinoma. Molecular analyses indicated a de-novo genesis of the invasive urothelial carcinoma.