 |
Vol.57 No.4 contents | Japanese/English |
 | Full Text of PDF (2849K) Article in Japanese |
- Case Report -
A Case of Metastasis to the Anterior Mediastinum from Carcinoma Showing Thymus-like Differentiation (CASTLE)
Joji Samejima1, Masaki Suzuki2, Tomoyuki Yokose2, Hiroyuki Ito1, Haruhiko Nakayama1, Munetaka Masuda31Department of Thoracic Surgery, 2Department of Pathology, Kanagawa Cancer Center, Japan, 3Department of Surgery, Yokohama City University School of Medicine, Japan
Background. Carcinoma showing thymus-like differentiation (CASTLE) is a rare low-grade neoplasm that arises from ectopic thymic tissue or the remnants of branchial pouches. CASTLE is considered to be an indolent slow-growing neoplasm with a favorable prognosis. Case. The patient was a 75-year-old man who had undergone left thyroid lobectomy 7 years previously. The histological diagnosis was anaplastic thyroid carcinoma. After surgery, he was treated with chemoradiotherapy (60 Gy of external radiation combined with carboplatin and paclitaxel). At 7 years after surgery, chest computed tomography showed a tumor of 14 mm in diameter in the anterior mediastinum. There was no evidence of local recurrence adjacent to the thyroid gland. It was suspected that the tumor was a thymoma or a recurrence of the thyroid neoplasm. We surgically resected the mediastinal tumor via video-assisted thoracoscopic surgery. The mediastinal tumor was cancer and showed squamous epithelial differentiation. The re-evaluation of the previous thyroidectomy specimen revealed that the histological findings of both neoplasms were similar. Immunohistochemical staining revealed that the specimen was focally positive for CD5 and positive for CD117. Based on these findings, the pathological diagnosis of the thyroid lesion was confirmed to be CASTLE, and the tumor of the anterior mediastinum was most likely mediastinal metastasis of CASTLE. Conclusion. CASTLE is a rare tumor that is difficult to differentiate from anaplastic thyroid carcinoma. Accordingly, we should carefully examine the immunohistochemical and pathological findings of such tumors.
key words: Metastasis, Mediastinum, Thyroid gland, Thymus
Received: March 14, 2017
Accepted: April 14, 2017
JJLC 57 (4): 292-298, 2017
