Surgery for Isolated Metachronous Thyroid Metastasis in a Non-small Cell Lung Carcinoma Patient with Hashimoto’s Thyroiditis: A Case Report

Non-small cell lung cancer (NSCLC) is the one of the leading causes of cancer deaths in Western population. Chemotherapy with platinum-based regimens is the first line management for majority of advanced NSCLC. Distant metastasis in lung cancer commonly involves the adrenal glands, liver, bones and brain. Metastatic involvement of the thyroid gland is infrequent despite its rich vascular supply. Here, we report a case of thyroid metastasis of NSCLC as a primary which was treated by thyroidectomy which is not the conventional approach. A 71 year-old female with a solitary left lower lobe lung mass was diagnosed with invasive poorly-differentiated adenocarcinoma. She was treated with cisplatin and pemetrexed followed by video-assisted thoracoscopic left lower lobectomy. The resected mass showed poorly-differentiated adenocarcinoma and was staged as pT2bN0 (Stage IIA). On a surveillance Computed Tomography (CT) chest, a left thyroid nodule was noted with findings consistent with Hashimoto's thyroiditis in a multinodular goiter. Fine-needle aspiration biopsy was consistent with metastasis from lung primary. This represented a solitary site of metastasis based on positron emission tomography (PET) Scan. Metastatic involvement of thyroid gland is infrequent despite its rich vascular supply. Given the long disease-free interval (DFI) of 1.5 years from initial diagnosis to documentation of isolated thyroid metastasis, she underwent total thyroidectomy followed by platinum-based adjuvant chemotherapy. Patient continues to be disease-free for more than 3 years as of her last follow up. A greater than 3-year disease-free survival to date in this case demonstrates that thyroidectomy can be a successful approach in the management of isolated metachronous thyroid metastasis from NSCLC in the well-selected patient.