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Multiple endocrine neoplasia type 2A — ABIM Board MCQ

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HardEndocrinology/MetabolismMultiple endocrine neoplasia type 2AABIM Board

A 33-year-old with episodic headache and sweating has a pheochromocytoma. His mother had medullary thyroid carcinoma, calcitonin is elevated and germline testing shows a pathogenic RET variant. He has hyperparathyroidism and no mucosal neuromas. Which syndrome is most likely?

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Correct answer: A — Multiple endocrine neoplasia type 2A with hyperparathyroidism

The best answer is “Multiple endocrine neoplasia type 2A with hyperparathyroidism”. MEN2A combines RET-associated medullary thyroid carcinoma, pheochromocytoma and sometimes primary hyperparathyroidism. MEN2B instead features mucosal neuromas and a marfanoid phenotype, while MEN1 involves parathyroid, pituitary and pancreatic endocrine tumors without medullary thyroid carcinoma. Primary hyperparathyroidism and the absence of mucosal neuromas distinguish MEN2A from MEN2B in this vignette.

Reference: American Thyroid Association Medullary Thyroid Carcinoma Guideline: https://pmc.ncbi.nlm.nih.gov/articles/PMC4490627/