Abstract
We report our experience with a patient who had a mediastinal cyst that was removed using a thoracoscope, and describe the results of the clinical diagnosis and classification based on a literature review. The patient was a male, aged 61, who visited a nearby doctor due to an abnormal shadow in the right posterior mediastinum that was found on a chest x-ray during a health screening. Retrospectively, a mass had been observed in that site 4 years before and had gradually increased in size at a rate of approximately 1mm per year. It was suspected to be a benign cystic lesion, and the patient was admitted to our hospital for surgery, partly because of the increasing size of the lesion, and partly because the patient requested a definite diagnosis. The results of CT, MRI and ultrasonic endoscopy suggested that the cystic lesion was connected to the internal orbicularis muscle of the esophagus and contained a viscous liquid. The lesion was, therefore, diagnosed as an esophageal cyst and the tumor was removed using a thoracoscope. Histologically, the lumen consisted of a pseudostratified ciliated columnar epithelium and was surrounded by connective, glandular and muscular tissues. It was difficult to distinguish the lesion from a bronchial cyst, but it was diagnosed as a foregut cyst, i.e., a cyst of foregut origin.
