General Considerations

• Developmental hamartomatous abnormality with cyst production
• 25% of all congenital lung lesions
• Communicate with the tracheobronchial tree
• Usually receives blood supply from pulmonary circulation and drains to pulmonary circulation
  • Types II and II may be associated with extralobar sequestration and receive systemic supply

Clinical Findings

• Most patients present in first month of life (70%) but sometimes discovered later in life because of recurrent pulmonary infections
• Usually present with respiratory distress

Imaging Findings

• The diagnosis can usually be made with conventional radiographs of the chest
• Equal predilection for each lung, slightly more common in upper lobes
• Lobar involvement is most common
• Prenatal ultrasound is accurate in diagnosing the disease usually at a mean gestational age of 22.6 weeks
• Early in life, the disease may present as a homogeneous, fluid-density mass because of delayed emptying of alveolar fluid, progressing to an air-filled cystic structure containing multiple air-fluid levels in cysts of varying size
  • Although multiple cysts may be present, it may appear as one large cyst initially
• Shift of the mediastinum away from the lesion
• There is air-trapping in the cysts which may lead to rapid enlargement
• The most frequent finding on CT are small cysts (<2cm) associated with larger cysts or consolidated lung

 

 

Differential Diagnosis

• Congenital lobar emphysema
  • Typically overexpansion of one lobe, most often an upper lobe
• Sequestration
  • May look identical to CCAM if infected with air-fluid levels
• Bronchogenic cysts
  • Well-circumscribed and fluid-filled

Treatment

• Surgical resection of the involved lobe in symptomatic patients

Complications

• May be associated with other congenital abnormalities up to 25% of time
  • More common with Type II lesions and include renal, intestinal, cardiac and osseous abnormalities

Prognosis

• Depends on size of lesion
  • Larger lesions are associated with vascular compromise, pulmonary hypoplasia and poorer prognosis
• Type III lesions are larger and have poorer prognosis   

 

 

Congenital cystic adenomatoid malformation (CCAM). Chest radiographs obtained on day 2 and 3 of life show an expanding, air-filled cystic lesion (white and yellow arrows) in the right lower lobe. The newborn also had hyaline membrane disease. A Ct scan of the same child shows a cystic lesion in the right lower lobe with septations (green arrow) and an air-fluid level (blue arrow).
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