Primary signet-ring cell carcinoma of the urinary bladder: a clinicopathologic and immunohistochemical study of 5 cases.

Primary signet-ring cell carcinoma of the urinary bladder is a rare histologic variant of adenocarcinoma. Generally, this neoplasm occurs in middle age and the clinical presentation does not differ from the most frequent transitional cell carcinomas. The prognosis is frequently poor as at diagnosis it is often in an advanced phase. It is essential to distinguish this carcinoma from metastases, as different therapeutic strategies are often necessary. We present 5 cases of primary signet-ring cell carcinoma of the urinary bladder and we used a panel of histochemical and immunohistochemical markers for differential diagnosis from secondary carcinoma in an attempt to elucidate the histogenetic derivation of this neoplasia.