The distinguishing feature of multiple endocrine neoplasia 2 B (MEN 2B) from multiple endocrine neoplasia 2 A (MEN 2A) is:

Medullary thyroid carcinoma and pheochromocytoma will be present in both. Parathyroid hyperplasia is a feature of MEN 2A. Mucosal and gastrointestinal neuroma and marfanoid features are seen in MEN 2B. MEN 2A MTC Pheochromocytoma Parathyroid hyperplasia or adenoma, MEN 2A with cutaneous lichen amyloidosis, MEN 2A with Hirschsprung disease MEN 2B MTC, Pheochromocytoma, Mucosal and gastrointestinal neuromas, Marfanoid features Ref:Harrisons Principles of Internal Medicine, 18th Edition, Page 3073