Neoplastic Paneth cells in adenocarcinoma of the urinary bladder: a first case report

A case of a highly differentiated, primary, nonurachal adenocarcinoma of intestinal type, originating from the urinary bladder mucosa, is reported. The tumor contained Paneth cells as an integrated part, and their identity on the light microscopic level was confirmed by histochemical stains including immunohistochemical stain for muramidase. A gradual change from Paneth cell types to mucous cells was seen. Argentaffin cells and goblet cells appeared in some parts of the tumor but no detectable transitional forms were found. Only a few carcinomas containing malignant Paneth cells have been recorded, and this case is believed to be the first observed in an extraintestinal site.