A 45-year-old man with MEN2A syndrome undergoes prophylactic thyroidectomy. In addition to medullary thyroid carcinoma (MTC), which other endocrine tumor characterizes MEN2A?

• A Pituitary adenoma (prolactinoma) and primary hyperparathyroidism
• B Pheochromocytoma and primary hyperparathyroidism (parathyroid hyperplasia or adenoma) ✓
• C Pheochromocytoma and cutaneous neuromas with marfanoid habitus (MEN2B features)
• D Insulinoma and VIPoma (pancreatic neuroendocrine tumors)

Explanation

MEN2A (Sipple syndrome) is caused by activating RET proto-oncogene mutations (most commonly codon 634 Cys→Arg). The triad consists of: (1) Medullary thyroid carcinoma (MTC, nearly 100% penetrance), (2) Pheochromocytoma (50%), and (3) Primary hyperparathyroidism (parathyroid hyperplasia/adenoma, 20–30%). MEN2B also has MTC and pheochromocytoma but features mucosal neuromas and marfanoid habitus without parathyroid disease. MEN1 syndrome involves pituitary, parathyroid, and pancreatic tumors (3 P's) due to MEN1 (menin) mutations.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.