Mediastinal Mass as First Clinical Manifestation of Medullary Thyroid Microcarcinoma in a Patient With Hashimoto’s Thyroiditis

Medullary thyroid cancer is a rare neuroendocrine tumor with aggressive behavior and an uncertain prognosis. Calcitonin the associated marker; however, tumors of lung or intestine can also present high values. We report case 53-year-old patient presenting dry cough for 3 years. Computed tomography (CT) showed 58-mm expansive lesion in right anterior mediastinum cervical ultrasound informed 9-mm hypoechoic nodule lobulated edge thick calcifications. Cytology reported Hashimoto’s thyroiditis. He underwent emergent surgery respiratory failure. The pathological study G2 carcinoma, immunohistochemistry showed: cytokeratin (+), vimentin alpha-actin (-), synaptophysin chromogranin Ki-67: 10%. progressed bone metastasis visualized scintigraphy mediastinal remnants, adenopathy, pulmonary nodules on CT scan, prompting chemotherapy. Due to elevated increasing calcitonin, needle washout calcitonin resulted 1,724 pg/mL, cytology medullary carcinoma. was finally diagnosed microcarcinoma mediastinum. Coexistence thyroiditis could alter initial fine-needle aspiration results. conclude that calcitonin-secreting cancer, fine aspirate may be helpful elucidating diagnosis. its severity, should always approached managed aggressively, even microcarcinomas. J Endocrinol Metab. 2022;12(6):198-201 doi: https://doi.org/10.14740/jem841