Prepared by Bacel Nseir, MD, Resident, Department of Internal Medicine/Pediatrics, and Stephanie Dewar, MD, Director, Pediatrics Residency Program, Northeastern Ohio Universities College of Medicine/Western Reserve Care System, Youngstown, Ohio
A 2-week-old female infant was brought to the emergency department with persistent tachypnea since birth. The tachypnea was continuous day and night and was associated with poor feeding. Vital signs were: temperature, 98.6°F; heart rate, 150 beats/min; respiratory rate, 70 breaths/min; pulse oximeter, 90% on room air.
Chest examination revealed bilateral retractions and accessory muscle use, absent breath sounds by auscultation, and hyperresonance by percussion over the left lung. The rest of the examination was unremarkable. Review of the chest radiograph (Figure 1) and the computed tomography (CT) scan of the chest (Figure 2) confirmed the diagnosis.
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| Figure 1. | Figure 2. |
What's Your Diagnosis?
- Congenital diaphragmatic hernia
- Congenital lobar emphysema
- Congenital cystic adenomatoid malformation
- Cystic hygroma
Quiz Answer
Congenital cystic adenomatoid malformation—The chest x-ray shows multiple large cysts in the left lung (Figure 1, arrows), as well as a loss of lung markings and a contralateral mediastinal shift. The CT scan shows the replacement of tissue in the entire left lung, with several cysts measuring 1 to 4 cm in diameter (Figure 2, arrows). These findings confirmed the physical examination findings (absence of breath sounds and hyperresonance over the left side), leading to the diagnosis.
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Congenital cystic adenomatoid malformation is a rare developmental anomaly of the lower respiratory tract that results from an abnormality of branching morphogenesis of the lung.1 Affected infants are typically symptomatic in the neonatal period, with evidence of tachypnea and dyspnea, as well as cyanosis. Recurrent pneumonia and poor feeding, with failure to thrive, are reported in fewer cases and may occur in mild forms of the disease.1,2 The diagnosis can usually be made by a plain chest radiograph; CT scans correlate with pathologic findings and may be helpful in confusing cases.2
The widespread use of antenatal ultrasound examination has resulted in increased prenatal diagnosis of congenital cystic adenomatoid malformation. Ultrasound imaging reveals microcystic lesions consisting of cysts <5 mm in diameter.
Prenatal magnetic resonance imaging may help distinguish congenital cystic adenomatoid malformation from congenital diaphragmatic hernia.1-3
Chest radiographs would detect a diaphragmatic defect in an infant with congenital diaphragmatic hernia.2 In congenital lobar emphysema, a CT scan would show a hyperlucent hyperexpanded lobe, without cystic formation.2 Cystic hygroma is most likely to occur where lymphatic tissue is located (ie, head, neck, axilla, groin, or retroperitoneal space).4
References
- Tawil MI, Pilling DW. Congenital cystic adenomatoid malformation: is there a difference between the antenatally and postnatally diagnosed cases? Pediatr Radiol. 2005;35:79-84.
- Williams HJ, Johnson KJ. Imaging of congenital cystic lung lesions. Paediatr Respir Rev. 2002;3:120-127.
- Duncombe GJ, Dickinson JE, Kikiros CS. Prenatal diagnosis and management of congenital cystic adenomatoid malformation of the lung. Am J Obstet Gynecol. 2002;187:950-954.
- Gallagher PG, Mahoney MJ, Gosche JR. Cystic hygroma in the fetus and newborn. Semin Perinatol. 1999;23:341-356.
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