Extrathyroid carcinoma showing thymus-like differentiation (CASTLE) tumor - A new case report and review of literature

Background. We report a case of extrathyroid carcinoma showing thymus-like differentiation (CASTLE) tumor. Methods. A 47-year-old man had a left neck mass that gradually enlarged over approximately 3 months. Sonography and CT scans showed a soft tissue mass located at the left parapharyngeal space with displacement of left carotid artery and submandibular gland. Results. After total excision, the pathologic diagnosis was CASTLE tumor. The patient then received radiotherapy with a total dosage of 6600 cGy. After 21 months of postoperative follow up, there was no evidence of recurrence. Conclusion. Generally, the treatment of choice is surgical excision with or without radiotherapy. Because CASTLE tumors have been reported to be radiosensitive, however, and because local recurrence is common, surgical excision with postoperative radiotherapy is suggested.