Metastatic Neuroendocrine Tumor in the Thyroid: Report of an Incidental Diagnosis

Abstract

Secondary tumors of the thyroid are quite rare with an estimated prevalence of < 1%. Herein, we describe the incidental discovery of metastatic small cell lung cancer in a non-toxic multinodular goiter. A 57-year-old lady has had a non-toxic multinodular goiter for over 10 years. She has had two thyroid fine needle aspirations (FNAs) in the past, which were reported benign. As the goiter was increasing in size and causing compression, she underwent a total thyroidectomy. Pathology revealed multi-centric high grade carcinoma with small cell/neuroendocrine features with the largest focus being 1.1 cm. Calcitonin staining was negative. Further imaging revealed a 68 × 37 × 51 mm soft tissue mediastinal mass and an 18 × 10 mm left upper lobe pulmonary nodule. She was then initiated on chemotherapy and radiation therapy for extensive stage small cell cancer of the lung. After two cycles of chemotherapy, restaging chest computed tomography (CT) showed interval improvement in lung masses. This rare presentation of small cell lung cancer with multi-centric metastasis to the thyroid highlights the need to obtain nodule directed FNAs, as the two non-directed FNAs done prior to surgery were benign. It also points out to clinicians that rapidly growing goiters are a cause for concern, and should be evaluated, even if patients are not symptomatic. J Endocrinol Metab. 2017;7(6):190-193 doi: https://doi.org/10.14740/jem468w