부산대학교 도서관

We report a case of primary squamous cell carcinoma （SCC） of the thyroid that was extremely difficult to diagnose and treat. A 76-year-old woman with hoarseness and discomfort when swallowing was referred to our hospital for a close examination for a suspected thyroid tumor. Laryngeal endoscopy revealed paramedian fixation of the right vocal cord, indicating right recurrent laryngeal nerve palsy. Computed tomography （CT） showed a nodular lesion in the right lobe of the thyroid contiguous to a hypodense lesion extending from the dorsal side of the right lobe to the upper mediastinum, which compressed the right common carotid artery. Fine needle aspiration cytology from the right lobe nodule showed class Ⅴ, whereas that from the hypodense lesion was class Ⅲ with atypical keratinized cells, suggesting a possibility of SCC. Positron emission tomography-CT （PET-CT）, gastrointestinal endoscopy, and bronchoscopy showed no possible primary lesion in other organs. Although we planned a complete resection of the tumor, rapid growth of the tumor during the work-up led to circumferential involvement of the right common carotid artery along with lung metastasis, which forced us to abandon the plan and only perform an excisional biopsy. Pathological evaluation with a series of immunohistochemical examinations determined the histological diagnosis of the tumor as SCC of the thyroid. In consideration of the unresectable status along with the high expression of PD-L1, combined pharmacotherapy consisting of CDDP and 5FU plus pembrolizumab was administered. Temporary suppression of the tumor growth and relief of the symptoms were observed, however, she eventually passed away about 8 months after the initial visit. SCC is an extremely rare histological type of thyroid-origin malignancy with a poor prognosis. In clinical practice of thyroid diseases, it is essential to keep in mind that there is another type of carcinoma that progresses remarkably fast besides undifferentiated carcinoma.