Background: Cystic adenomatoid malformation, a rare pulmonary malformation, usually appears as a cystic mass, radiologically. It may be infected and confusion has also arisen in distinguishing it from pneumonia with pneumatoceles.
Case reports: A full-term boy suffered from severe neonatal respiratory distress. Pregnancy had been uneventful despite the fact that his mother had insulin-dependent diabetes. Prenatal ultrasonographies did not reveal any abnormality. On day 2, X-rays showed a right pulmonary mass that appeared solid. The patient was treated for E Coli sepsis. Subsequently, the pulmonary mass became lacent, cystic, fluid-filled, resembling an abscess; the CT scan confirmed these features. As the lesion increased in volume, a limited resection was performed. Histologic examination showed adenomatoid proliferation of bronchiolar elements with formation of cysts and necrosis.
Conclusion: Infection of cystic adenomatoid malformation may supervene the first days of life resulting in a lung abscess appearance.