Neuroendocrine tumor in a horseshoe kidney. Case report and updated follow-up of cases reported in the literature.

Renal neuroendocrine tumors (NET) are rare neoplasms of unknown histogenesis. To the best of our knowledge, 40 such cases have been described, 11 of which arising in horseshoe kidneys (HSK). We report an additional case of a NET associated with a HSK occurring in a 45-year-old man. A clinicopathological review of the reported cases together with an updated follow-up of such tumors arising in HSK is provided. The present data show that NET associated with HSK present a better prognosis than those occurring in normal kidneys, even over long-term follow-up periods. 2004 S. Karger AG, Basel.