Leiomyosarcoma of the urinary bladder: a diagnostic challenge in urine cytology.

Most of the available data in the literature describe the cytomorphological features of exfoliated malignant epithelial cells in urine. There are no established diagnostic features that characterize the morphology of exfoliated malignant mesenchymal tumor in urine. Here we highlight the problems in the diagnosis of these groups of tumors. The presence of discohesive atypical cells which lack features of an epithelial nature should make one suspicious of this group of tumors. 2004 Wiley-Liss, Inc.