Spindle cell lesions of the bladder and urinary tract.

Spindle cell lesions of the urinary tract encompass a variety of benign and malignant tumours as well as a group of lesions of controversial nomenclature that is the subject of ongoing debate. This review focuses on our current and evolving understanding of the lesion variably referred to as inflammatory myofibroblastic tumour, pseudosarcomatous myofibroblastic proliferation or inflammatory pseudotumour and the main differential diagnoses of sarcomatoid carcinoma and sarcoma. Other spindle cell lesions of the bladder are described.