What distinguishes MEN 2B from MEN 2A?

MEN 2B is characterized by the presence of mucosal neuromas, which are a distinct feature that helps differentiate it from MEN 2A. Mucosal neuromas are benign growths occurring in the mucosal membranes, commonly found in the lips and tongue, and they can lead to a phenotype associated with this syndrome.

In addition to mucosal neuromas, patients with MEN 2B often present with a marfanoid habitus, which is also a distinguishing feature but is not as specific to MEN 2B as the presence of mucosal neuromas.

MEN 2A typically includes parathyroid hyperplasia or adenomas, medullary thyroid carcinoma, and pheochromocytoma, but it does not involve the mucosal neuromas seen in MEN 2B. Therefore, the identification of mucosal neuromas is a key diagnostic factor for MEN 2B and sets it apart from MEN 2A.