Lymphoepithelial cysts in the mediastinum with an opening to the trachea.

A case of lymphoepithelial cysts (LECs) in the mediastinum, manifested radiographically by paratracheal air collection, is reported. Percutaneous injection of radiopaque material and indocyanine green into a cyst showed an opening to the trachea. During surgical resection, three well-circumscribed cysts were isolated. Pathologically the cysts were lined by a ciliated columnar epithelium and surrounded by lymphoid tissue with germinal centers. Judging from the level of the duct opening onto the airway, these LECs might have derived from a remnant of the fourth branchial pouch. To the authors' knowledge, this is the first case described.