Familial multiple endocrine neoplasia syndromes: components, classification, and nomenclature.

There are three generally accepted multiple endocrine neoplasia (MEN) syndromes: MEN-1, MEN-2A, and MEN-2B. On the basis of their major features, new familial MEN syndromes should manifest (i) a new endocrine tumour combination, (ii) autosomal dominant inheritance, and, possibly, (iii) a nonendocrine component. Acceptance of the last feature as a criterion has conferred candidate MEN status on a number of disorders, including von Hippel-Lindau disease and neurofibromatosis. To regard these conditions as MEN syndromes would require an inappropriate demotion of their predominant nonendocrine manifestations. The role of nonendocrine disorders in MEN syndromes needs reappraisal.