Collecting duct carcinoma of kidney: a cytological study and case report.

An intraoperative cytological imprint of a well study case of collecting duct carcinoma of the kidney is reported. Papillary structures, fibrotic desmoplastic stroma, tubular formations, and tumoral cells with high grade cytological atypia were found. Cytological details described help to avoid misinterpretation of collecting duct carcinoma as a metastatic tumor. The peculiar morphology, the immunohistochemical and biological behavior of this rare tumor justifies its classification in a special group.