All of the following are components of the MEN type 2B syndrome except:

B. Hyperparathyroidism.

DISCUSSION: MTC and pheochromocytoma occur in both MEN 2A and MEN 2B syndromes. Patients with MEN 2A may also develop hyperplasia of the parathyroid glands. Although some investigators have reported equivocal histologic abnormalities in the parathyroid glands of patients with MEN 2B, hyperparathyroidism is not a component of this syndrome. In contrast to patients with MEN 2A, those with MEN 2B have a characteristic phenotype, including a tall, thin “marfanoid” habitus. Patients with MEN 2B also develop multiple neuromas on the lips, tongue, and oral mucosa, creating the appearance of thick lips.