Congenital diaphragmatic hernias are most commonly diagnosed as lethal anomalies in neonates or infants. In adults, congenital hernias can present as an incidental finding or may be associated with nonspecific symptoms. The presence of a basal lung mass due to the presence of herniated abdominal contents in the thoracic cavity can appear dramatic on imaging and the unwary can be led into making a wrong diagnosis. We report a case of an incidentally diagnosed rightsided Bochdalek hernia in a young woman and discuss the developmental anomalies leading to this pathology.