ODP503 Non-Small Cell Lung Cancer Metastatic to the Thyroid Gland

Abstract

Abstract Introduction Metastatic disease affecting the thyroid gland is an uncommon phenomenon, with the most common primary sites being kidney, breast, lung and gastrointestinal tract. Thyroid metastases frequently occur simultaneously with spread to other sites and are rarely symptomatic. Clinical case: 73-year-old female with remote history of stage IA (T1c, N0, M0) invasive lobular carcinoma of the right breast treated with lumpectomy, radiation and tamoxifen, previous tobacco use, remote exposure to radiation during Chernobyl nuclear accident, developed progressive dyspnea on exertion. She was found to have a large left-sided pleural effusion. Thoracentesis was performed, and the cytology revealed adenocarcinoma with features favoring lung primary. Further imaging showed a left lower lobe mass with central necrosis and left hilar adenopathy, multiple pleural masses, and a small solitary brain lesion. PET-CT also demonstrated, amongst other findings, an FDG avid left lower pole thyroid nodule. Thyroid ultrasound was obtained to further characterize the lesion, which demonstrated a 0.8×1.3×1.3 cm solid hypoechoic nodule in the left mid lobe, which was thought to be corresponding to the PET avid nodule. Two additional nodules, a mixed cystic and solid measuring 1.7×2.1×2.9 cm on the right lobe, and another left-sided solid isoechoic measuring 0.8×0.7×0.9 cm, were noted. Thyroid FNA of the 1.3 cm PET avid nodule revealed rare cells in clusters, with large pale nuclei and prominent nucleoli, some with intracytoplasmic vacuoles, morphologically similar to those seen in the prior pleural fluid. Thin prep was stained with antibody to thyroglobulin, and the malignant cells showed lack of staining, supporting the diagnosis of metastatic lung cancer. Thyroid function tests were normal. Given lack of compressive symptoms, patient was maintained on her primary oncologic treatment with carboplatin and pemetrexed, and stereotactic radiation for the brain metastasis. Repeat PET-CT, performed approximately 8 months after the initial scan, showed mildly decreased focal FDG activity in the thyroid lesion. Discussion In this scenario, a patient with primary lung malignancy was found to have an FDG avid thyroid nodule which on FNA proved to be a metastatic lesion. Per some studies, such lesions can be seen in 1.4%–3% of patients who undergo surgery for suspected malignancy in the thyroid gland. Management of metastatic thyroid cancers depends on multiple factors including the primary malignancy location and staging, patient comorbidities, compressive symptoms, etc. Surgical management may be of benefit in isolated lesions in the thyroid. Conclusion When evaluating thyroid nodules in patients with known history of malignancy, it is important to consider the differential of metastatic lesions and to perform a thorough evaluation including fine-needle aspiration for clinical elucidation and management. Presentation: No date and time listed