A 47-year-old woman was diagnosed with anaplastic thyroid carcinoma….Postoperative pathology revealed that the right thyroid mass was classic papillary carcinoma...The results of genetic testing showed that BRAF V600E was negative and TERT gene was positive. No targetable gene mutation was found in the patient and the immune index PDL1 was positive (PDL1 22C3, CPS=10)....Subsequently, tislelizumab immunotherapy was recommended as a treatment choice. The patient has been treated with tislelizumab at a dose of 200 mg every three weeks from July 2021. Tislelizumab immunotherapy was well tolerated and almost no adverse reactions were observed in the patient. Her neck mass was gradually reduced in size after radiotherapy and tislelizumab immunotherapy.