The most common clinical features of MEN2B are:
a tall, thin, "marfanoid" body build, in which long bones are disproportionately elongated;
masses beneath mucosal surfaces in the mouth, lips, and eyes (discussed below);
low muscle mass, sometimes with myopathy;
gastrointestinal complaints, especially constipation;
symptoms derived from medullary carcinoma of the thyroid;
symptoms derived from pheochromocytoma;
craniosynostosis;
dry eyes or lack of tears, which is an especially helpful sign in children;
delayed puberty.

Unlike Marfan syndrome, the cardiovascular system and the lens of the eye are unaffected.
Mucosal neuromas are the most consistent and distinctive feature, appearing in 100% of patients.
Usually there are numerous yellowish-white, sessile, painless nodules on the lips or tongue, with deeper lesions having normal coloration.
There may be enough neuromas in the body of the lips to produce enlargement and a "blubbery lip" appearance.
Similar nodules may be seen on the sclera and eyelids.

Histologically, neuromata contain a characteristic adventitious plaque of tissue composed of hyperplastic, interlacing bands of Schwann cells and myelinated fibers overlay the posterior columns of the spinal cord.
Mucosal neuromas are made up of nerve cells, often with thickened perineurium, intertwined with one another in a plexiform pattern.
This tortuous pattern of nerves is seen within a background of loose endoneurium-like fibrous stroma.
The most common clinical features of MEN2B are:
a tall, thin, "marfanoid" body build, in which long bones are disproportionately elongated;
masses beneath mucosal surfaces in the mouth, lips, and eyes (discussed below);
low muscle mass, sometimes with myopathy;
gastrointestinal complaints, especially constipation;
symptoms derived from medullary carcinoma of the thyroid;
symptoms derived from pheochromocytoma;
craniosynostosis;
dry eyes or lack of tears, which is an especially helpful sign in children;
delayed puberty.
Unlike Marfan syndrome, the cardiovascular system and the lens of the eye are unaffected. Mucosal neuromas are the most consistent and distinctive feature, appearing in 100% of patients. Usually there are numerous yellowish-white, sessile, painless nodules on the lips or tongue, with deeper lesions having normal coloration. There may be enough neuromas in the body of the lips to produce enlargement and a "blubbery lip" appearance. Similar nodules may be seen on the sclera and eyelids.
Histologically, neuromata contain a characteristic adventitious plaque of tissue composed of hyperplastic, interlacing bands of Schwann cells and myelinated fibers overlay the posterior columns of the spinal cord. Mucosal neuromas are made up of nerve cells, often with thickened perineurium, intertwined with one another in a plexiform pattern. This tortuous pattern of nerves is seen within a background of loose endoneurium-like fibrous stroma.
Multiple endocrine neoplasia type 2B