Two cases of histologically, immunohistochemically, and ultrastructura
lly confirmed collecting duct carcinoma of the kidney (CDCK) with posi
tive urine cytology are reported. The patients' urine sediments showed
malignant glandular cells in sheets with defined, variable, granular
cytoplasm and oval, hyperchromatic nuclei containing micro- or macronu
cleoli. The cytologic differential diagnosis of CDCK is briefly discus
ses. (C) 1997 Wiley-Liss, Inc.