A Case of Thymic Basaloid Carcinoma That Developed After Resection of Lung and Rectal Cancer

━━ Background. Thymic cancer is an uncommon neoplasm. In particular, thymic basaloid carcinoma is extremely rare. Case. A 71-year-old male with a history of surgery for primary lung cancer and rectal cancer exhibited an elevated serum level of carcinoembryonic antigen (CEA) with an anterior mediastinal cyst and tumor on a computed tomography scan. Fluorodeoxyglucose-positron emission tomography showed a high stan-dardized uptake value (SUV) max value of 8.4 at the mediastinal tumor site with no additional uptake throughout the body. The patient underwent tumor resection via median sternotomy. The histopathological findings revealed a thymic basaloid carcinoma (pT2N0M0, stage II and Masaoka stage II). Adjuvant radiation therapy was administered, and the patientʼs CEA level normalized. Unfortunately, multiple bone metastases, right adrenal me-tastasis and an elevated serum CEA level developed 13 months after resection. The patient is currently undergo-ing palliative radiotherapy for the bone lesions. Conclusions. We herein reported a rare case of thymic basaloid carcinoma that developed after lung and rectal cancer resection. Solitary lesions with a cystic component in the mediastinum should therefore be accurately diagnosed and resected, even after resection of a prior malignancy.