Collecting duct carcinoma of the kidney: a report of three cases and review of the literature.

Collecting duct carcinoma (CDC) of the kidney is a rare neoplasm arising from the medullary collecting ducts. The clinicopathological features of three cases are here presented to add to the 42 cases reported so far in the English language literature. Hematuria is the most common presenting symptom, although 10% of patients present with metastatic disease, often in neck lymph nodes. The tumor mass is typically centred on the medulla of the kidney and extends into the cortex. Radiological diagnosis may be difficult because the radiological features of CDC are poorly described. The histological appearances have been described as tubulo-papillary, tubular, solid and sarcomatoid. Intracytoplasmic mucin may be present. The typical immunohistochemical profile is positive staining with antibodies for low and high molecular weight keratin and epithelial membrane antigen (EMA) and positive staining with the lectin Ulex europaeus agglutinin. Literature reports of cytogenetic characterisation show loss of chromosomes resulting in monosomies. Prognosis is poor as more than half of the reported cases have developed metastases or died within two years of presentation.