Three Cases of Collision Cancer of Squamous Cell Carcinoma and Adenocarcinoma

Background. Primary pulmonary collision tumor is relatively rare. We report three cases of primary pulmonary collision cancer. Case. Case 1 was a 67-year-old man in whom an abnormal shadow, a tumor 2cm in diameter in the right S10, was found on a chest X-ray film and bronchofiberscopic cytology showed squamous cell carcinoma of the lung. Right lower lobectomy was performed and the pathologic diagnosis showed collision cancer of adenocarcinoma and squamous cell carcinoma. Case 2 was a 77-year-old man. His chest X-ray film and CT showed a tumor in the right S6. Right lower lobectomy was performed and pathologic diagnosis showed collision cancer of adenocarcinoma and squamous cell carcinoma. Case 3 was a 75-year-old woman in whom chest X-ray film and CT showed a tumor 2.7cm in diameter in the right S2. Biopsy via bronchofiberscopy showed squamous cell carcinoma. After right upper lobectomy, pathologic diagnosis showed collision cancer of adenocarcinoma and squamous cell carcinoma. Conclusion. These three cases were all collision tumors involving adenocarcinoma and squamous cell carcinoma which is the most common combination in lung cancer.