[Bladder sarcomatoid carcinoma. Bladder carcinoma simulating lymphoma].

Objective: To describe an unusual type of vesical carcinoma (sarcomatoid carcinoma) associated with the spread of inflammation. The article discusses the diagnostic difficulties and prognosis.
Method/results: We describe a patient with vesical sarcomatoid carcinoma associated with the spread of inflammation that practically obscured the undifferentiated area, mimicking a lymphoma. This is interpreted as a favourable immunological reaction, despite the highly aggressive behaviour of the sarcomatoid component.
Conclusions: Only on rare occasions do vesical carcinomas present such a prominent degree of spindle-shaped cells. This finding could create some diagnostic confusion, hence an immunohistochemical study is essential. The identification of sarcomatoid carcinoma has important implications both for treatment and for prognosis. The literature refers to the marked aggressiveness of this type of tumour. The peculiarity of the case resides in the associated spread of inflammation which improved the prognosis.