Pulmonary Small Cell Carcinoma with Thyroid and Cerebellum Metastases
Abstract
Pulmonary small cell carcinoma typically metastasizes to lymph nodes, liver, adrenal glands, brain, and pleura; thyroid involvement is exceptionally rare. A 57-year- old woman presented with an eight-month history of progressive dyspnea. Clinical examination revealed an enlarged thyroid gland with palpable nodules in both lobes. Contrast-enhanced chest CT demonstrated a lobulated right hilar mass extending into the posterior mediastinum. CT-guided biopsy of the hilar lesion confirmed small cell lung carcinoma on histopathology. Fine needle aspiration of the thyroid nodules yielded hypercellular smears containing medium-sized round cells with hyperchromatic nuclei. To exclude primary medullary thyroid carcinoma with pulmonary metastasis, serum calcitonin and carcinoembryonic antigen (CEA) were measured, revealing levels of 20 pg/mL and 49.91 ng/mL, respectively. Integrating these findings, the diagnosis of pulmonary small cell carcinoma with thyroid metastasis was established. This case underscores that, although rare, the thyroid gland can serve as a metastatic site for small cell lung carcinoma. Therefore, in patients with a known primary malignancy, the appearance of a new thyroid nodule warrants prompt evaluation for possible metastatic disease.