Snap Shot A mass found in the mediastinum on routine imaging and was removed. Introduction Tumors of brachial cleft cells that contain ectoderm, endoderm, mesoderm. Dermoid cyst is a teratoma made out of ectodermal derivatives (teeth, skin, hair) Found in anterior mediastinum 15% are malignant Malignant if invades surrounding tissues Evaluation CT X-ray shows teeth or calicifications AFP, CEA are tumor markers Surgical Managment Surgical resection with preoperative chemo if malignant