Rare tumours in domestic animals: a lipid cell variant of urothelial carcinoma of the urinary bladder in a cow and a case of vesical carcinosarcoma in a dog

Neoplasms of the urinary bladder have a low incidence in domestic animals. In dogs they account for less than 1% of all reported neoplasms (Confer and Panciera, 2001). Cattle grazing on bracken fern-infested lands are at increased risk of suffering from tumours of the urinary bladder (Galati, 1997). It has been suggested that long term urine storage plays an important role in urothelial carcinogenesis since it could enhance the action of carcinogenic agents as it increases urine contact time with tissue (Caywood et al., 1980). It has been suggested that primary epithelial tumours of the urinary bladder occur more frequently in female than male dogs with an average age of 10 years (Crow, 1985). About 76% of all urinary bladder tumours develop from the urothelium, and most of them are malignant (Caywood et al., 1980; Strafuss et al., 1975). The recent WHO Histological classification of urinary bladder tumours in humans (Mostofi and Davis, 1999) describes some new variants of urothelial carcinoma that have not yet been reported in animals. In an ongoing research program about the incidence of urinary bladder tumours at the Department of Veterinary Pathology at Naples Veterinary School, two new cases were observed: a lipid cell variant of urothelial carcinoma in a cow and a carcinosarcoma in a dog.