Pulmonary Collision Tumor Comprising Lung Adenocarcinoma and Metastatic Endometrial Cancer: A Case Report

We report a rare case of a 78-year-old woman with a collision tumor composed of primary lung adenocarcinoma and metastatic endometrial cancer. The patient previously underwent hysterectomy and adjuvant chemotherapy for Stage IIIC1 endometrial cancer. Chest computed tomography (CT) revealed a ground-glass nodule in the right upper lobe, which was suspected to be inflammatory scarring. Two years later, new adjacent nodules emerged, both of which gradually increased in size and exhibited partial collisions. A lobectomy was performed to detect multiple synchronous lung cancers. Histological features of the surgical specimens included acinar adenocarcinoma and metastatic lung tumors of endometrial cancer. To the best of our knowledge, this is the first report of a pulmonary collision tumor consisting of a lung adenocarcinoma and a metastatic lung tumor of endometrial cancer, with serial CT imaging successfully capturing the collision between the two lesions.