Although thyroid tumors are commonly primary, metastases are extremely rare. We report a rare case of metastatic adenocarcinoma of primary lung origin presenting as a solitary thyroid nodule. A 55-yearold female housewife with no significant past medical history, admitted to our emergency department, complained of anterior neck swelling and dyspnea for one month. In radiological assessment, goiter with retrosternal extension, right primary pulmonary mass with bilateral pleural effusion, and metastases of the brain, thyroid, mediastinal lymph node, and left lung were detected. Dyspnea improved after chest drainage. Cytological examination and biopsies were performed, and histopathological and immunohistochemical examinations revealed primary lung adenocarcinoma and thyroid metastasis. The patient was discharged after pleurodesis without complications. Even though primary tumors of the thyroid are more common and usually benign, metastasis should always be kept in mind, especially in patients with a positive history of renal cell, breast, and lung cancer.
Keywords: Thyroid, metastasis, lung cancer