A newborn presents with respiratory distress during feeding.The male infant was delivered by induced vaginal delivery due to prolonged rupture of membranes. Delivery was complicated by 1-minute shoulder dystocia. After delivery, the infant initially was limp, with no respiratory effort, but responded well to positive pressure ventilation with spontaneous respirations at 2 minutes after birth. Apgar scores were 2, 4, 7, and 8 at 1, 5, 10, and 15 minutes, respectively. He was transferred to the neonatal intensive care unit (NICU) because of tachycardia, grunting, and apneic spells. Blood cultures were taken, antibiotics were started, and he was placed on 2 L/min oxygen via nasal cannula. A chest radiograph demonstrated clear lungs bilaterally. His cultures were negative, and his respiratory distress resolved quickly. He received a total of 48 hours of antibiotics. He was discharged from the hospital 3 days after birth. Two days later, he developed a fever and cyanosis during a feeding. At the emergency department, his temperature was101.3°F (38.5°C). Blood and urine were obtained for culture, and a lumbar puncture was performed. He was started again on antibiotics and admitted to the NICU. Routine chest radiography showed a cystlike structure in the right lower lobe (RLL).Chest computed tomography scan showed a well-defined, multilocular, 2.2x2.5x3-cm cystic lesion with no arterial supply from the aorta, confirming the diagnosis of CCAM. Surgical consultation was obtained. Over the next 48 hours, the patient fed well, with no noted tachypnea or cyanosis. All cultures of blood, urine, and cerebrospinal fluid were negative at 48 hours. He was discharged with ongoing follow-up by pediatric surgery. At 3-month follow-up, the boy was feeding and growing well, but chest radiography showed the enlarging lesion taking up most of the right lung field. He underwent wedge resection of the lesion. Pathologic examination of the specimen was consistent with type 1 CCAM. He tolerated the procedure without difficulty and remains symptom-free at 8 months of age.CCAM is a rare developmental anomaly of the lower respiratory tract that occurs sporadically and has no known genetic predisposition. The reported incidence is 1 per 11,000 to 1 per 35,000 live births, with males being marginally more commonly affected. CCAM results from an abnormality of branching morphogenesis of the lung. The malformations are comprised of hamartomatous lesions made up of cystic and adenomatous growth of the terminal bronchioles and air spaces. The arterial supply and venous drainage from the lesions are from the pulmonary circulation. The different types of CCAMs are believed to originate at different levels of the tracheobronchial tree and at different stages of lung development.Four types of CCAMs were described by Stocker:When Type 3 lesions are present, fetal hydrops and pulmonary hypoplasia typically develop. Infants may be stillborn or present immediately after birth with severe and progressive respiratory distress, cyanosis, and respiratory failure.Patients affected with CCAM may present with respiratory distress in the newborn period or may remain asymptomatic until later in life. Most CCAMs that present in newborns are type 1. Typical presenting signs include tachypnea, increased respiratory effort with grunting and retractions, and cyanosis. Many cases now are detected on routine prenatal ultrasonography.Treatment depends upon whether the patient has symptomatic or asymptomatic disease. Surgical resection is the definitive treatment in those who have symptomatic disease. Typically, a lobectomy is preferred to wedge resection because of the technical difficulty in identifying planes of dissection with some lesions and the increased morbidity associated with partial resections.Because of an ongoing risk of infection and malignancy in rare cases, asymptomatic patients also are treated with surgical resection. The timing of such surgery is controversial. Reviews of a patient cohort seen over a 10-year period by Calvert and associates suggested that 3 to 6 months of age is an optimal time period for surgery. Aziz and colleagues documented that 17 of 35 patients who had CCAM remained asymptomatic for up to 3 years. No long-term data indicate whether this approach improves outcome.The prognosis for CCAM depends on the type of malformation. Surgical excision in the neonatal period is curative for most type 1 lesions, and the prognosis excellent. The remaining lung parenchyma undergoes compensatory growth. The outcome of type 4 CCAM also is good with surgical resection. The prognosis for types 2 and 3 CCAM are not as favorable. The outcome may be affected by the severity of associated congenital anomalies in infants who have type 2 lesions. Those who have type 3 lesions frequently have severe hypoplasia of the contralateral lung and may develop pulmonary hypertension. Due to the severe derangement in fetal development, Type 0 is not compatible with life.JoDee M. Anderson, MD, Division of Neonatal Medicine, Oregon Health & Science University, Portland, OR