A Large Congenital Pulmonary Airway Malformation Mimicking a Cystic Thoracic Mass in an Infant: A Case Report.

Congenital pulmonary airway malformation (CPAM) is a rare developmental anomaly of the lung that can present with a wide spectrum of clinical manifestations, ranging from asymptomatic incidental findings to severe respiratory compromise during infancy. We present the case of a one-year-old male infant with a giant multicystic pulmonary lesion involving the right upper and middle lobes, causing significant mediastinal shift and respiratory symptoms. The patient presented with recurrent episodes of lower respiratory tract infection, persistent cough, and progressive shortness of breath. Clinical examination revealed reduced air entry over the right upper and middle lung fields. Chest imaging demonstrated a large multicystic lesion almost completely replacing the right upper and middle lobes. CT of the chest revealed a purely multicystic mass lesion without a visible solid component, abnormal vasculature, or communication with the bronchial system. The lesion produced a significant mass effect with a contralateral mediastinal shift. Based on the clinical and radiological findings, CPAM was considered the most likely diagnosis. The patient underwent surgical resection with right upper and middle lobectomy. Histopathological examination confirmed the diagnosis of CPAM. The postoperative course was uncomplicated with resolution of respiratory symptoms and satisfactory clinical recovery during follow-up. This case highlights the importance of considering CPAM in infants presenting with recurrent respiratory symptoms and complex cystic lung lesions. Large lesions may remain undiagnosed until infancy and can produce significant anatomical distortion through compression of adjacent lung tissue and mediastinal displacement. Detailed radiological assessment is essential for characterization of the lesion, exclusion of vascular anomalies, and operative planning. Early recognition and appropriate surgical management of symptomatic CPAM can provide excellent outcomes and prevent potential complications associated with persistent abnormal lung tissue.