RESUMO
OBJECTIVE: We report 2 cases of small cell neuroendocrine carcinomas (CCP) of the urinary bladder in patients aged 37 and 80 years. CCP is a malignancy with poor prognosis. We review the literature, under the current WHO classification (2016). METHODS: Paraffin blocks were cut for HE staining and immunohistochemistry to analyze the expression of neuroendocrine differentiation. RESULTS: The main diagnosis was based on histopathologic features, which revealed a diffuse growth pattern of small cells with scant cytoplasm and hyperchromatic nuclei. The result of the additional technical immunoreaction was positive for synaptophysin and CD56. CONCLUSIONS: Our cases have been reviewed with the literature to discuss the evolution and differential diagnosis of small cell carcinoma of the urinary bladder. This is a rare tumor with very aggressive behavior and its diagnosis lies in its morphology, and immunohistochemical profile.