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Multiple endocrine neoplasia (MEN) is characterized by a predilection for tumors involving two or more endocrine glands. Four major forms of MEN are recognized and referred to as MEN types 1–4 (MEN 1–4) (Table 52-1). Each type of MEN is inherited as an autosomal dominant syndrome or may occur sporadically; that is, without a family history. However, this distinction between familial and sporadic forms is often difficult because family members with the disease may have died before symptoms developed. In addition to MEN 1–4, at least six other syndromes are associated with multiple endocrine and other organ neoplasias (MEONs) (Table 52-2). These MEONs include the hyperparathyroidism-jaw tumor syndrome, Carney complex, von Hippel-Lindau disease (Chap. 53), neurofibromatosis type 1 (Chap. 48), Cowden’s syndrome, and McCune-Albright syndrome; all of these are inherited as autosomal dominant disorders, except for McCune-Albright syndrome, which is caused by mosaic expression of a postzygotic somatic cell mutation (Table 52-2).
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