The multiple endocrine neoplasia (MEN) syndromes comprise 3 genetically distinct familial diseases involving adenomatous hyperplasia and malignant tumors in several endocrine glands.
MEN 1 Multiple Endocrine Neoplasia, Type 1 (MEN 1) Multiple endocrine neoplasia, type 1 (MEN 1) is a hereditary syndrome characterized by hyperplasia or sometimes adenomas of the parathyroid glands, pancreatic islet cell tumors (also known as... read more involves primarily hyperplasia or sometimes adenomas of the parathyroid glands (with resultant hyperparathyroidism Primary hyperparathyroidism Hypercalcemia is a total serum calcium concentration > 10.4 mg/dL (> 2.60 mmol/L) or ionized serum calcium > 5.2 mg/dL (> 1.30 mmol/L). Principal causes include hyperparathyroidism... read more ) and tumors of the pancreatic islet cells and/or pituitary gland.
MEN 2A Multiple Endocrine Neoplasia, Type 2A (MEN 2A) Multiple endocrine neoplasia, type 2A (MEN 2A) is a hereditary syndrome characterized by medullary carcinoma of the thyroid, pheochromocytoma, parathyroid hyperplasia or adenomas (causing hyperparathyroidism)... read more
involves primarily medullary thyroid carcinoma, pheochromocytoma, hyperplasia or sometimes adenomas of the parathyroid glands (with resultant hyperparathyroidism), and occasionally cutaneous lichen amyloidosis.MEN 2B Multiple Endocrine Neoplasia, Type 2B (MEN 2B) Multiple endocrine neoplasia, type 2B (MEN 2B) is an autosomal dominant syndrome characterized by medullary thyroid carcinoma, pheochromocytoma, multiple mucosal neuromas and intestinal ganglioneuromas... read more
involves primarily medullary thyroid carcinoma, pheochromocytoma, multiple mucosal and intestinal neuromas, and marfanoid habitus.
Clinical features depend on the glandular elements involved.
Each syndrome is inherited as an autosomal dominant trait with a high degree of penetrance, variable expressivity, and production of seemingly unrelated effects by a single mutant gene. The specific mutation is not always known.
Symptoms and signs develop at any age. Proper management includes early identification of affected individuals within a kindred and surgical removal of the tumors when possible. Although these syndromes are genetically and clinically distinct, significant overlap exists (see table Conditions Associated With MEN Syndromes Conditions Associated With Multiple Endocrine Neoplasia Syndromes 
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