Micropapillary, sarcomatoid, and small cell carcinoma are uncommon, aggressive variants usually encountered in the evolution of high-grade nonpapillary transitional cell carcinoma. Of these, only small cell is effectively treated with currently available systemic therapy, with recent evidence suggesting a role for neoadjuvant chemotherapy. While adenocarcinoma and squamous cancers can also arise from the urothelium, neither is as sensitive to chemotherapy as conventional transitional cell carcinoma. Dominant lymphoepithelioma has a favorable prognosis. Urachal cancers require preoperative recognition for optimal surgical management, and are being shown to be somewhat responsive to regimens useful in colon cancer. Mesenchymal tumors are exceedingly rare and are treated like other pelvic sarcomas.
- Small cell
ASJC Scopus subject areas