Adenocarcinoma with neuroendocrine differentiation of the urinary bladder. Clinicopathologic, immunohistochemical, and ultrastructural study.

We describe a primary mixed adenocarcinoma-neuroendocrine carcinoma of the urinary bladder of probable urachal origin. Neuroendocrine differentiation was confirmed by ultrastructural (neurosecretory granules) and immunohistochemical studies (chromogranin and neuron-specific enolase). Two local recurrences and multiple metastases consisted exclusively of the neuroendocrine component. The patient died 30 months after diagnosis with widely metastatic neuroendocrine carcinoma.