Bronchogenic Cyst: A usually spherical cyst, arising as an embryonic out-pouching of the foregut or trachea. It is generally found in the mediastinum or lung and is usually asymptomatic unless it becomes infected.Carcinoma, Bronchogenic: Malignant neoplasm arising from the epithelium of the BRONCHI. It represents a large group of epithelial lung malignancies which can be divided into two clinical groups: SMALL CELL LUNG CANCER and NON-SMALL-CELL LUNG CARCINOMA.Mediastinal Cyst: Cysts of one of the parts of the mediastinum: the superior part, containing the trachea, esophagus, thoracic duct and thymus organs; the inferior middle part, containing the pericardium; the inferior anterior part containing some lymph nodes; and the inferior posterior part, containing the thoracic duct and esophagus.Esophageal Cyst: Any fluid-filled closed cavity or sac (CYSTS) that is lined by an EPITHELIUM and found in the ESOPHAGUS region.Bronchopulmonary Sequestration: A developmental anomaly in which a mass of nonfunctioning lung tissue lacks normal connection with the tracheobroncheal tree and receives an anomalous blood supply originating from the descending thoracic or abdominal aorta. The mass may be extralobar, i.e., completely separated from normally connected lung, or intralobar, i.e., partly surrounded by normal lung.Diverticulum, Esophageal: Saccular protrusion beyond the wall of the ESOPHAGUS.Cysts: Any fluid-filled closed cavity or sac that is lined by an EPITHELIUM. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues.Radiography, Thoracic: X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs.Atrial Septum: The thin membrane-like muscular structure separating the right and the left upper chambers (HEART ATRIA) of a heart.Pulmonary Surgical Procedures: Surgery performed on the lung.Thoracotomy: Surgical incision into the chest wall.Thoracoscopy: Endoscopic examination, therapy or surgery of the pleural cavity.Diagnostic Techniques, Surgical: Methods and procedures for the diagnosis of disease or dysfunction by examination of the pathological site or operative field during surgical intervention.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Retroperitoneal Space: An area occupying the most posterior aspect of the ABDOMINAL CAVITY. It is bounded laterally by the borders of the quadratus lumborum muscles and extends from the DIAPHRAGM to the brim of the true PELVIS, where it continues as the pelvic extraperitoneal space.