A 29-year-old pregnant woman from Syria was screened for tuberculosis upon arrival in the Netherlands. The chest X-ray showed a smooth sharply demarcated mass in her left upper lobe. A low-dose CT showed that the mass was lobulated and surrounded by a hyperlucent pulmonary segment. To protect the foetus from further exposure to radiation, an MRI was performed, which confirmed bronchial atresia with a mucocele of the distal bronchus.