Primary Thyroid Squamous Cell Carcinoma With Complete Response to Radical Surgery and Concurrent Chemoradiotherapy: Diagnostic Pathologic Workup and Clinical Management

Abstract

Abstract Primary squamous cell carcinoma (SqCC) of the thyroid gland is an extremely rare, highly aggressive malignancy associated with locally advanced disease and frequent metastases to regional lymph nodes and distant sites. There are no standardized guidelines for treating primary thyroid SqCC because of its rarity, but some investigators have recommended staging and treating it as a variant of anaplastic thyroid carcinoma. Prognosis, however, remains poor with minimal response to treatment and an estimated median survival of 6 to 14 months. We report a case of primary SqCC of the thyroid that was successfully treated with aggressive locoregional resection followed by concurrent radical dose radiotherapy and cisplatin-based chemotherapy. The patient remains free of disease more than 4 years after surgery and adjuvant chemoradiation. Because of potential prognostic and management implications, it is crucial to make an accurate pathologic diagnosis of primary SqCC of the thyroid and distinguish it from metastatic squamous carcinoma and other primary thyroid malignancies with squamous features. A thorough clinicopathologic diagnostic workup including immunohistochemistry, computed tomography scan, and endoscopy is mandatory. In this case, treatment similar to the standard management used for patients with locally advanced mucosal head and neck squamous cancer led to a successful outcome.