Thymic Carcinoma With Endobronchial Metastasis: A Case Report

Thymic carcinoma is a rare cancer, accounting for only 1% to 4% of thymic epithelial tumors. Endobronchial metastasis is a rare presentation of these tumors. A 64-year-old man presented with a cough. Lung cancer was suspected because a chest radiograph showed a 7-cm mass in the left pulmonary hilum. Computed tomography showed a mass in the anterior mediastinum and an infiltrate in the upper lobe of the left lung. Bronchoscopy demonstrated bilateral polypoid tumors in the left B bronchus and the right B bronchus. Endobronchial biopsies of both lesions resulted in a diagnosis of squamous cell carcinoma that was positive for c-KIT by immunohistochemical staining. The patient was eventually found to have thymic squamous cell carcinoma with bilateral endobronchial metastases (stage IVb according to the Masaoka-Koga staging system) by diagnostic video-assisted thoracoscopic surgery. He was subsequently treated with platinum-doublet chemotherapy and achieved a partial response for 18.8 months.