The purpose of this paper is to examine the case of a 50-day-old patient with an unusual and severe presentation of a rare disease: congenital cystic adenomatoid malformation of the lung. The infant was admitted to the pediatric intensive care unit with respiratory failure and circulatory collapse refractory to intravenous fluids and inotropic drugs. Chest X-ray showed a radiolucent homogeneous image in the right lung base, suggesting bullous lesion of the right lower lobe associated with ipsilateral pneumothorax. Drainage was performed by placing a chest tube with subsequent clinical improvement. Later the cyst was resected by right lower lobectomy; the histopathological diagnosis was congenital cystic adenomatoid malformation type 4 (Stocker classification). The patient evolved favorably.