Histopathology of urinary bladder carcinoma: less common variants

Bladder cancer is a common form of neoplasia which most often presents histologically as urothelial (transitional cell) carcinoma. In this article we review recent publications dealing with the less common variants of urothelial carcinoma such as tumours that show unusual forms of differentiation or the well know squamous, glandular, or sarcomatoid differentiation. Urothelial tumours may also show several distinct growth variants characterized by a nested, micropapillary, lymphoepithelioma-like, or plasmacytoid and giant cell growth pattern.The clinical course of bladder cancer varies depending on the histological type of neoplasia, grade and stage of the tumour. High-grade muscle-invasive urothelial cancers and tumours showing variant microscopic morphology have in general high mortality and poor prognosis.