Adult Congenital Pulmonary Airway Malformation Presenting With a Large Cystic Lung Lesion: A Case Report.

Congenital pulmonary airway malformation (CPAM) is a rare developmental lung malformation that is usually diagnosed antenatally or during early childhood. Adult presentation is uncommon and may present a significant diagnostic challenge because of overlapping radiological features with other cystic lung diseases and malignancy. We report the case of a 49-year-old man with an incidentally detected large multiseptated cystic lesion occupying almost the entire right upper lobe. CT and PET-CT suggested a congenital cystic lung lesion without evidence of metabolically active malignancy. Following multidisciplinary discussion, the patient underwent video-assisted thoracoscopic wedge resection. Histopathological examination demonstrated benign cystic pulmonary changes without evidence of malignancy. The patient made an excellent postoperative recovery, with complete radiological resolution and objective improvement in pulmonary function. This case highlights the importance of considering CPAM in the differential diagnosis of large cystic pulmonary lesions in adults. Multidisciplinary assessment and surgical resection remain essential for establishing a definitive diagnosis and achieving favorable clinical outcomes.