Multiple endocrine neoplasia, type 2a

Multiple endocrine neoplasia type 2 (MEN 2) includes the following phenotypes: MEN 2A, FMTC (familial medullary thyroid carcinoma, which may be a variant of MEN 2A), and MEN 2B. All three phenotypes involve high risk for development of medullary carcinoma of the thyroid (MTC); MEN 2A and MEN 2B involve an increased risk for pheochromocytoma; MEN 2A involves an increased risk for parathyroid adenoma or hyperplasia. Additional features in MEN 2B include mucosal neuromas of the lips and tongue, distinctive facies with enlarged lips, ganglioneuromatosis of the gastrointestinal tract, and a marfanoid habitus. MTC typically occurs in early childhood in MEN 2B, early adulthood in MEN 2A, and middle age in FMTC.

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