Chemoradiotherapy as a pivotal therapeutic modality for inoperable intrathymic thyroid carcinoma: A case report and literature review.

RATIONALE: Intrathyroid thymic carcinoma (ITTC) is a rare group of low-grade malignant tumors, for which surgery is the treatment of choice. However, there is little evidence on the effectiveness of radiotherapy and chemotherapy in the treatment of ITTC. PATIENT CONCERNS: A 50-year-old man presented with a 6-month history of a neck obstruction sensation. Clinical examination revealed a firm, fixed mass in the right thyroid lobe. DIAGNOSES: Imaging and biopsy confirmed locally advanced, unresectable ITTC with tracheal and esophageal invasion. Diagnosis was supported by immunohistochemistry (CD5+, CD117+). INTERVENTIONS: Given the unresectable nature of the tumor, the patient was treated with definitive chemoradiotherapy. This consisted of induction chemotherapy with a docetaxel and cisplatin regimen, followed by concurrent chemoradiotherapy. OUTCOMES: Treatment achieved a complete response. The patient remained disease-free at 40-month follow-up. LESSONS: Multimodal regimens with chemoradiotherapy backbone may achieve durable remission for unresectable ITTC, providing an alternative when surgery is contraindicated.