[An experience with surgical treatment for mucoepidermoid carcinoma of the lungs].

Mucoepidermoid carcinoma (MEC) of the lungs is thought to arise in the bronchial glands. It is a tumor that rarely develops and it has a low grade of malignancy. In this paper, we describe one case of infiltrative MEC, which we were able to diagnose preoperatively. Surgery revealed a high grade malignancy which is reported here with a discussion based on the related literature. The patient was a 63-year-old male who was referred to our hospital by another physician due to a cough and left chest pain. A simple chest X-ray revealed a tumor shadow and a fascicular shadow on its periphery in the upper left lobe. Bronchoscopy disclosed complete circumferential stenosis at B1+2,3 and reddening from this region to the main bronchus, but it was impossible to directly confirm the tumor. Pulmonary arterography did not depict the left upper pulmonary vein, but obstruction due to a tumor of that vein was observed. Given the above findings, under a diagnosis of infiltrative MEC, a left total lobectomy accompanied by a combined left atriectomy was performed. Although most cases of MEC have a low grade malignancy, there have been some reported cases with a very high grade of malignancy. Therefore, evaluation of the progress of this type of carcinoma by preoperative diagnosis as well as radical excision appropriate to lung cancer are considered to be important.