Rare <i>RET</i> Variants in a Patient With MEN2A and Multiple Follicular-Derived Thyroid Tumors: A Case Report and Review of the Literature

Multiple endocrine neoplasia (MEN) syndromes are a group of rare autosomal dominant hereditary disorders that are classified into 5 distinct types. MEN2A, the most common type of MEN2, is associated with mutations and variants of <i>RET</i>, which are continually being updated. However, studies regarding <i>RET</i> mutations/variants related to MEN2A in the Chinese population are scarce, and patients involving MEN2A along with other differentiated thyroid tumors are rarer. We report a 54-year-old Chinese woman diagnosed with MEN2A and multiple follicular-derived thyroid tumors. Ultrasonography and computed tomography revealed a nodule in the thyroid and a nodule in the left adrenal gland. Laboratory investigations revealed elevated levels of both calcitonin and parathyroid hormone. The patient also had an 8-year history of hypertension, which normalized following the adrenal mass resection. Pathology identified 3 types of thyroid tumors and one type of adrenal tumor: the thyroid tumors consisted of medullary thyroid carcinoma, follicular adenoma, and papillary thyroid carcinoma, while the adrenal tumor was pheochromocytoma. Whole exome sequencing identified multiple germline mutations in the <i>RET</i> proto-oncogene, specifically R114H, A432A, and G691S. This report suggests that <i>RET</i> variants in MEN2A patients from the Chinese population may differ from the common <i>RET</i> variants. Additionally, MEN2A patients may present with thyroid follicular epithelial-derived tumors; however, further studies are necessary to determine any potential associations with <i>RET</i> variants.