Collecting duct carcinoma of kidney.

Collecting duct carcinoma of the kidney is a rare neoplasm with only approximately 100 cases described in the literature to date. The tumor occurs in a wide age range and predominantly in males. Typical collecting duct carcinoma consists of a grossly infiltrative neoplasm centered on the renal medulla. The usual histological pattern is that of a tubular or tubulopapillary carcinoma with a desmoplastic stroma that often contains neutrophils. Less commonly, collecting duct carcinoma has a papillary architecture with desmoplasia and infiltrative growth. Collecting duct carcinoma spread aggressively and many patients have metastases at the time of presentation. Origin in the collecting duct is suggested by medullary location, dysplasia of the epithelium in collecting ducts outside the tumor, and reactivity with antibody to high molecular weight cytokeratin and Ulex europaeus agglutinin. No unifying cytogenetic or molecular genetic features have been discovered thus far. The concept of collecting duct carcinoma is expanding and should include the recently described renal medullary carcinoma that is associated with sickle cell trait.