Methicillin Resistant Staphylococcus Aureus Colonization, The Tip of the Iceberg for Congenital Pulmonary Airway Malformation. A Case Report.

Background: Congenital Pulmonary Airway Malformation (CPAM) is a rare congenital anomaly of the lung that is infrequently diagnosed in the neonatal period, especially in preterm infants without prenatal detection. Methicillin-Resistant Staphylococcus aureus (MRSA) colonization and infection in preterm neonates can further complicate diagnosis and clinical progression. Aim: To describe a rare presentation of CPAM diagnosed in a preterm neonate following late-onset MRSA sepsis, emphasizing the diagnostic challenge and the interplay between infection and congenital malformation. Methods: We present a case report of a preterm female infant (28+3 weeks gestational age, birth weight 1100g), the second of twins, with an initially unremarkable postnatal chest X-ray. She developed clinical deterioration on day 17 of life, and investigations revealed MRSA colo-nization and positive tracheal aspirate cultures. Progressive radiological changes led to further imaging and diagnosis of CPAM. A systematic literature review was also conducted to identify similar cases of CPAM in preterm neonates. Results: Initial imaging showed no signs of pulmonary malformation. However, after the onset of MRSA-related late-onset sepsis (LOS), follow-up imaging revealed a multiloculated cystic lesion in the right upper lobe. A CT scan confirmed a differential diagnosis of CPAM type II versus necrotizing pneumonia. Surgical lobectomy was performed on day 40 of life, and histopathology confirmed CPAM type I with focal mucinous metaplasia. Postoperative recovery was successful, and the infant was discharged home in stable condition on day 90 of life. Discussion/Conclusion: This case highlights the possibility that MRSA sepsis may serve as a trigger or unmasking event for underlying CPAM in preterm neonates. The absence of antenatal diagnosis and delayed radiological changes in this case emphasize the need for a high index of suspicion in the setting of localized pulmonary pathology during systemic infection. In reviewing the literature, this represents one of the few documented cases of CPAM in a preterm neonate without prenatal suspicion. Prompt recognition and multidisciplinary management are essential for optimizing outcomes in such complex cases.