Primary squamous thyroid cancer: A case report

Primary squamous cell carcinoma of the thyroid (PSCCT) is a rare malignancy characterized by low incidence, high aggressiveness and poor prognosis, with no established standardized treatment guidelines. The present case involves a 66-year-old female who presented with a painless left neck mass discovered incidentally in July 2023. The mass progressed over two months, accompanied by dyspnea. In September 2023, surgical intervention confirmed a poorly differentiated thyroid carcinoma (6.0×5.0 cm, invading the anterior cervical muscles; Ki-67 ≈60%, mutant-type p53) in the left lobe and nodular goiter in the right lobe. The patient underwent left radical thyroidectomy and right lobectomy (no lymph node metastasis detected in 9 central compartment nodes). Postoperative PD-L1 testing revealed high expression (CPS=50). From November 2023 to February 2024, the patient completed 6 cycles of chemotherapy (albumin-bound paclitaxel + carboplatin) combined with immunotherapy (tislelizumab). Partial radiotherapy (16/25 fractions) was initiated in March 2024 but discontinued due to radiation-induced mucositis and leukopenia. Follow-up in June 2024 demonstrated complete response (CR) with no evidence of recurrence. This case achieved complete response (CR) through multidisciplinary integrated therapy, providing clinical evidence for PSCCT treatment optimization. Given the rarity and therapeutic uncertainty of PSCCT, our study highlights: The critical value of immunohistochemistry (CK19+, CK5/6+, TTF-1-, TG-) in differential diagnosis; Potential benefits of immunotherapy in PD-L1-high expressors; The necessity of combining surgery with systemic therapies and demand for individualized strategies.