Abstract
A 63-year-old woman who underwent a left hepatic lobectomy for hilar cholangiocarcinoma was referred to our department for further management. Chest computed tomography showed a lung nodule that was increased in size to 8 mm in the S4a. The differential diagnosis was metastasis versus primary lung cancer. Thoracoscopic left S4a subsegmentectomy was performed. The operative time was 158 min. The blood loss was minimal. Air leakage was not observed, and a chest tube was removed on POD 1. The patient was discharged home on POD 3. The final diagnosis was primary lung cancer (T1aN0M0 stage IA). Surgical margin was 2.0 cm.