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Multiple Endocrine Neoplasia, Type 2B (MEN 2B)

(Mucosal Neuroma Syndrome; Multiple Endocrine Adenomatosis, Type 2B)


Patricia A. Daly

, MD, University of Virginia;

Lewis Landsberg

, MD, Northwestern University Feinberg School of Medicine

Last review/revision Apr 2021 | Modified Sep 2022
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Multiple endocrine neoplasia, type 2B (MEN 2B) is an autosomal dominant syndrome characterized by medullary thyroid carcinoma, pheochromocytoma, multiple mucosal neuromas and intestinal ganglioneuromas, and often a marfanoid habitus and other skeletal abnormalities. Symptoms depend on the glandular elements present. Diagnosis and treatment are the same as for MEN 2A.

Symptoms and Signs of MEN 2B

Often, mucosal neuromas are the earliest sign, and they occur in most or all patients. Neuromas appear as small glistening bumps on the lips, tongue, and buccal mucosae.

The eyelids, conjunctivae, and corneas also commonly develop neuromas; infants are often unable to make tears. Thickened eyelids and everted, diffusely hypertrophied lips are characteristic.

Gastrointestinal abnormalities related to altered motility (constipation, diarrhea, and, occasionally, megacolon) are common and thought to result from diffuse intestinal ganglioneuromatosis.

Patients almost always have a marfanoid habitus Symptoms and Signs Marfan syndrome consists of connective tissue anomalies resulting in ocular, skeletal, and cardiovascular abnormalities (eg, dilation of ascending aorta, which can lead to aortic dissection)... read more Symptoms and Signs . Skeletal abnormalities are common, including deformities of the spine (lordosis, kyphosis, scoliosis), slipped capital femoral epiphyses, dolichocephaly (hull-shaped skull, also called scaphocephaly), pes cavus, and talipes equinovarus.

Medullary thyroid carcinoma and pheochromocytoma resemble the corresponding disorders in MEN 2A syndrome; both tend to be bilateral and multicentric. Medullary thyroid carcinoma, however, tends to be particularly aggressive in MEN 2B and may be present in very young children.

Although the neuromas, facial characteristics, and gastrointestinal disorders are present at an early age, the syndrome may not be recognized until medullary thyroid carcinoma or pheochromocytoma manifests in later life.

Diagnosis of MEN 2B

  • Clinical suspicion

  • Genetic testing

  • Plasma free metanephrines and urinary catecholamine levels

  • Pheochromocytoma localization with magnetic resonance imaging (MRI) or computed tomography (CT)

MEN 2B is suspected in patients with a family history of MEN 2B, pheochromocytoma, multiple mucosal neuromas, or medullary thyroid carcinoma. Genetic testing is highly accurate and is done to confirm the disorder. Genetic testing Screening 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 Screening also is done to screen 1st-degree relatives and any symptomatic family members of patients with MEN 2B, as in MEN 2A.

Pheochromocytoma Diagnosis A pheochromocytoma is a catecholamine-secreting tumor of chromaffin cells typically located in the adrenals. It causes persistent or paroxysmal hypertension. Diagnosis is by measuring catecholamine... read more may be suspected clinically and is confirmed by measuring plasma free metanephrines and urinary catecholamines. Laboratory testing for medullary thyroid carcinoma Medullary Thyroid Carcinoma with serum calcitonin measurements should be done. MRI or CT is used to search for pheochromocytomas and medullary thyroid carcinoma.

Treatment of MEN 2B

  • Surgical excision of identified tumors

  • Prophylactic thyroidectomy

Affected patients should have total thyroidectomy as soon as the diagnosis is established. Pheochromocytoma, if present, should be removed before thyroidectomy is done.

Gene carriers should undergo prophylactic thyroidectomy before age 1 year.

Key Points

  • Multiple endocrine neoplasia, type 2B (MEN 2B) has a mutation of the same gene as in MEN 2A and manifests similarly except for the absence of hyperparathyroidism, the presence of more aggressive medullary thyroid carcinoma and the presence of multiple mucosal neuromas and a marfanoid habitus.

  • Patients should have genetic testing for RET proto-oncogene mutations and blood or urine tests for pheochromocytoma.

  • Pheochromocytoma is excised and prophylactic thyroidectomy is done.

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