Endocrinology Question 2

Answer & Critique

Correct Answer: C

Educational Objective: Diagnose the multiple endocrine neoplasia type 2 (MEN2) syndrome.

Key Point

Medullary thyroid cancer, pheochromocytoma, and primary hyperparathyroidism occur in patients with multiple endocrine neoplasia type 2A (MEN2A).

This patient is most likely to develop primary hyperparathyroidism. He has symptoms related to catecholamine excess from a pheochromocytoma and has a personal and family history of medullary thyroid cancer. This is typical of multiple endocrine neoplasia type 2A (MEN2A) resulting from a mutation in the RET proto-oncogene. Primary hyperparathyroidism due to multiple gland hyperplasia frequently occurs in patients with MEN2A. Patients with primary hyperparathyroidism may present with symptoms related to hypercalcemia (polydipsia, polyuria, and constipation), or the hyperparathyroidism may be found during an evaluation for osteoporosis or nephrolithiasis. Pheochromocytomas in MEN2A are usually benign and intra-adrenal in location, but can be multiple or bilateral.

Insulinoma and prolactinoma occur in multiple endocrine neoplasia type 1 (MEN1). In MEN1, one mutated allele of the MEN1 gene is usually inherited, and a somatic mutation in the other allele is later acquired and results in the formation of neoplasia. The most common endocrine disorder in MEN1 is primary hyperparathyroidism resulting from one or more parathyroid adenomas.

Neurofibroma is not a clinical feature of MEN2A. Neurofibromas, café-au-lait spots, and pheochromocytoma are among the clinical features of the autosomal dominant disorder neurofibromatosis type 1.


Krampitz GW, Norton JA. RET gene mutations (genotype and phenotype) of multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma. Cancer. 2014 Jul 1;120(13):1920-31. PMID: 24699901

This content was last updated in January 2016.

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