Resident Physician Rochester General Hospital rochester, New York, United States
Introduction : Medullary thyroid carcinoma (MTC) accounts for 1%-2% of thyroid cancers in the United States. It was first described in the early 1900s as thyroid cancer with amyloid, however it was only until 1959 that a definitive histological description was recognized. Multiple endocrine neoplasia type 2 (MEN2) is a rare neoplastic syndrome that includes MTC, pheochromocytoma, and hyperparathyroidism. MEN 2A represents 95% of MEN2. MTC is present in almost all MEN 2A cases while pheochromocytoma is present in approximately 50% and hyperparathyroidism in only 10-20% of patients.
Case(s) Description : We present the case of a 72 year old male with history of hypothyroidism, multinodular goiter and type II diabetes mellitus, who was diagnosed with MEN 2A syndrome. He presented to our endocrinology clinic after an incidental finding of a right thyroid nodule on chest CT scan. He was asymptomatic and denied family history of thyroid cancer or personal history of neck radiation. A thyroid ultrasound showed a 1.2 cm complex nodule of the left thyroid lobe, and a large 6 cm complex nodule replacing the right thyroid lobe. FNA showed discohesive epithelial cells with plasmacytoid and columnar morphology suggestive of MTC. Afterwards, blood work was checked and showed elevated calcitonin, parathyroid hormone (PTH), and carcinoembryonic antigen (CEA). Plasma metanephrine and normetanephrine were within normal range. Patient underwent total thyroidectomy with central and right neck dissection, and parathyroidectomy. Pathology demonstrated multifocal tumor with clear margins and no vascular invasion or extrathyroid extension, however 3 out of 17 lymph nodes were involved. Final pathological classification was pT2N1a. Genetic testing showed mutation Leu790Phe on exon 13.
Discussion : MEN2 is a rare autosomal dominant hereditary disease that involves MTC, pheochromocytoma and hyperparathyroidism. MTC typically occurs in early adulthood in MEN 2A. Affected patients are generally asymptomatic. A complete workup including calcitonin, CEA, PTH level and a detailed family history should be obtained. RET proto-oncogene genetic testing is key in the diagnosis of patients with MTC. L790F is a moderate risk mutation that is typically associated with higher incidence of pheochromocytoma and lower incidence of hyperparathyroidism. Interestingly enough, our patient had a late diagnosis of MEN 2A at the age of 73, including MTC and hyperparathyroidism, and had L790F mutation.
