Medullary carcinoma of the thyroid in the multiple mucosal neuromas syndrome.

The clinical features of the multiple mucosal neuromas (MMN) syndrome permit the recognition of these patients and their potential development of the associated medullary thyroid carcinoma (MTC). The distinctive physical appearance caused by the mucosal neuromas, the Marfanoid habitus and, occasionally, the positive family history aid in establishing the diagnosis. Neurogangliomas are frequently present in the gastrointestinal tract of these patients who may have megacolon, constipation and diarrhea. The third instance of the MMN syndrome is reported in the newborn as intestinal obstruction. It is suggested that the syndrome be considered in the differential diagnosis of Hirschsprung's disease and bowel obstruction in the neonate. Serum calcitonin measurements following stimulation by calcium or pentagastrin infusion reliably detect incipient MTC and may be used to select those MMN patients requiring thyroid surgery. Recognition of patients with the MMN syndrome and subsequent calcitonin screening and early surgical intervention will significantly reduce the chance of their developing terminal MTC. All MMN patients with mucosal neuromas or intestinal neurogangliomas should have such evaluations at least yearly. Relatives who are at risk for inheriting this dominant disease should be similarly evaluated, regardless of their normal appearance.