Neuroendocrine tumours of the urinary system and male genital organs: clinical significance.

Two basic types of neuroendocrine (NE) tumours with diverse clinicopathological features and outcome are identified in the urinary system and male genital organs: carcinoid tumour and neuroendocrine carcinoma. Carcinoid, a rare tumour, occurs in the kidney, bladder, prostate and testis. It is morphologically, histochemically, immunohistochemically and ultrastructurally similar to its counterpart in other organs, such as lung or gastrointestinal tract. Metastases can be detected at the initial evaluation, although they have been reported up to several years after removal, emphasizing the need for a long-term follow-up. NE carcinoma occurs in the kidney, bladder and prostate, and includes small cell carcinoma (SCC) and large cell NE carcinoma (LCNEC), the latter being exceedingly rare. Both show the morphology and immunophenotype of NE carcinoma originating in other organs. Although the occurrence is rare, it is highly aggressive.