Salvage Surgery after Pembrolizumab Treatment for Squamous Cell Carcinoma of the Thyroid Gland: A Case Report and Review of the Literature

Abstract

Background/Aim: Squamous cell carcinoma of the thyroid is a rare disease with a poor prognosis, and a standard treatment has not yet been established. Case Report: This report details the response of an 80-year-old woman diagnosed with squamous cell carcinoma of the thyroid to pembrolizumab treatment. She was referred to our hospital with the chief complaints of hoarseness and dyspnoea. Further examination revealed a tumour in the left lobe of the thyroid gland infiltrating the left side of the thyroid cartilage, along with oedema in the left lumbar region and left recurrent nerve palsy. Owing to the risk of asphyxia, the patient was urgently admitted to the hospital, and tracheotomy and tumour biopsy were performed. Subsequently, primary squamous cell carcinoma of the thyroid gland (cT4aN0M0) was diagnosed. The patient did not wish to undergo surgical treatment; therefore, radiotherapy was administered, but it proved ineffective and was subsequently discontinued. Biopsy tissue analysis indicated a combined positive score >20; consequently, pembrolizumab was introduced, which exhibited a notable antitumour effect which led to a significant reduction in tumour size. Positron emission tomography-computed tomography performed during the course of treatment revealed FDG enhancement of the tumour, indicating reaggravation. Following consultation with the patient, total thyroidectomy and laryngectomy were performed. Postoperative histopathology unexpectedly revealed no evidence of squamous cell carcinoma in the tumour tissue, and only papillary carcinoma of the thyroid gland. This suggests that pembrolizumab may have resulted in the complete resolution of squamous cell carcinoma of the thyroid gland. Conclusions: Pembrolizumab may be an effective treatment modality for squamous cell carcinoma of the thyroid.journal articl