Unveiling the Expected: A Case Report of a Massive Congenital Lung Cyst in a 22-Year-Old Male.

Congenital pulmonary airway malformations (CPAMs) are predominantly identified prenatally or during infancy, with adult-onset cases being considered extremely rare. This case report describes a 22-year-old male who presented with hemoptysis and exertional dyspnea, leading to the diagnosis of CPAM. The patient had experienced small-volume hemoptysis for four years, which escalated to larger volumes and progressive dyspnea one week before hospital admission. A chest CT scan revealed a large 13.2 cm thin-walled cavitary lesion with an air-fluid level in the left lower lobe. The patient underwent left video-assisted thoracoscopic surgery (VATS) resection, which confirmed a CPAM originating from the left lower lobe. The postoperative recovery was uneventful, and the patient was symptom-free at follow-up. This case highlights the need to consider CPAM in the differential diagnosis of respiratory symptoms in young adults, even without congenital anomalies or predisposing factors. Early recognition and surgical intervention can lead to favorable outcomes.