Carcinoid syndrome produced by an isolated metastase in femoral nerve from a midgut carcinoid tumor

Dear Editor: Carcinoid tumors are slow-growing neoplasms derived from enterochromaffin cells or Kulchintsky cells being thus neuroendocrine in nature. They may arise anywhere in the gastrointestinal tract, in the bronchi, and occasionally elsewhere (ovary, central nervous system). Within the gastrointestinal tract, most carcinoid tumors arise in the small intestine (45 %, most commonly in the ileum), followed by rectum (20 %), appendix (16 %), colon (11 %), and stomach (7 %). Carcinoid syndrome is the term applied to a set of symptoms mediated by different humoral factors elaborated by some carcinoid tumors (diarrhea, cutaneous flushing, cardiac valvular lesions, bronchospasm, and intermittent abdominal pain). These tumors synthesize, store, and release a variety of polypeptides, biogenic amines, and prostaglandins. Some of these tumor products are responsible for the carcinoid syndrome. The relative contribution and the specificity of each of the particular components of the syndrome are uncertain. It seems that among patients with intestinal carcinoid tumors, the carcinoid syndrome does not occur in the absence of liver metastases. In contrast, bronchial and other extraintestinal carcinoids, whose bioactive products are not immediately cleared by the liver, can rarely cause the syndrome in the absence of metastatic disease. Metastases of carcinoid tumors in peripheral nerve are extremely rare. All of them come from supradiaphragmatic