A congenital pulmonary airway malformation (CPAM) is a rare cystic anomaly that may occur during development of the fetal airways. The vast majority of CPAMs are detected in neonates; as such, it is unusual for diagnosis to occur in adulthood. We report a 21-year-old male patient who presented to the emergency department of the Hospital Ampang, Kuala Lumpur, Malaysia, in 2015 with chest pain, breathlessness and tachypnoea. Based on an initial chest X-ray, the patient was misdiagnosed with pneumothorax and underwent urgent chest tube insertion; however, his condition deteriorated over the course of the next three days. Further imaging was suggestive of infected bullae or an undiagnosed CPAM. The patient therefore underwent video-assisted thoracoscopic surgery, during which a large infected bulla was resected. A diagnosis of an infected CPAM was confirmed by histopathological examination. Following the surgery, the patient recovered quickly and no bullae remnants were found at a one-month follow-up.Keywords: Respiratory System Abnormalities; Congenital Cystic Adenomatoid Malformation of Lung; Adult; Respiratory Tract Infection; Pneumothorax; Video-Assisted Thoracic Surgery; Case Report; Malaysia.

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