A Rare Case of Thyroid Metastasis Secondary to Hidden Undiagnosed Lung Adenocarcinoma

The majority of thyroid lesions are primary in origin while secondary metastases to thyroid are considered a rare incidence. However, presentation of such cases with no signs of lung cancer can be extremely challenging to diagnose. Here, we present a 64-year-old man, an ex-smoker of 70 pack-years, who presented with a complaint of hoarseness of voice with associated dyspnea, choking episodes, weight loss, and hemoptysis. With no investigation abnormalities indicating lung adenocarcinoma, he was transferred to the Otolaryngology Department as being suspicious of thyroid cancer. A laryngoscopy demonstrated an immobile right vocal cord and pooling of secretions while a computed tomography (CT) scan showed a right thyroid lobe nodule, upper mediastinal lymphadenopathy, and pleural effusion. The patient underwent a total thyroidectomy. Biopsies from the lymph nodes and lung were obtained, and all demonstrated lung adenocarcinoma. Thus, a diagnosis of primary lung adenocarcinoma with thyroid and mediastinal lymph nodes metastases was established. Despite being a rare clinical presentation, thyroid metastasis should be considered and evaluated for a primary origin according to the associated clinical history and presentation.