[10] The most common clinical features of MEN2B are:[citation needed] Unlike Marfan syndrome, the cardiovascular system and the lens of the eye are unaffected.

[11] Usually there are numerous yellowish-white, sessile, painless nodules on the lips or tongue, with deeper lesions having normal coloration.

[citation needed] 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.

[12] Mucosal neuromas are made up of nerve cells, often with thickened perineurium, intertwined with one another in a plexiform pattern.

Gordon et al. reported cases of a difference disease—the "multiple mucosal neuroma syndrome"—having the physical phenotype of MEN2B, but without variations in the RET gene and without malignancy.

Calcitonin levels remain a valuable marker to detect recurrence of medullary thyroid carcinoma after thyroidectomy.

[citation needed] Luxol fast blue staining identifies myelin sheathing of some fibers, and lesional cells react immunohistochemically for S-100 protein, collagen type IV, vimentin, NSE, and neural filaments.

Details are lacking, owing to the absence of formal studies, but it is generally assumed that death in the 30s is typical unless prophylactic thyroidectomy and surveillance for pheochromocytoma are performed (see below).

[citation needed] Because prophylactic thyroidectomy improves survival, blood relatives of a person with MEN2B should be evaluated for MEN2B, even if lacking the typical signs and symptoms of the disorder.

[citation needed]The mucosal neuromas of this syndrome are asymptomatic and self-limiting, and present no problem requiring treatment.

[20] This theory suggests Lincoln had all the major features of the disease: a marfan-like body habitus, large, bumpy lips, constipation, muscular hypotonia, a history compatible with cancer, a family history of signs suggestive of the disorder (in his sons Eddie, Willie, and Tad, and probably his mother).

The "mole" on Lincoln's right cheek, the asymmetry of his face, his large jaw, his drooping eyelid, and "pseudo-depression" are also suggested as manifestations of MEN2B.