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Congenital Cystic Adenomatoid Malformation

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


Types of CCAM




Most common; composed of 1 or more cysts measuring 2-10 cm in size, larger cysts often associated with smaller cysts; walls contain muscle, elastic, or fibrous tissue. Cyst walls occasionally produce mucin which is unique to this subtype.


Small cysts (0.5-2 cm) of relatively uniform size resembling bronchioles; lined by cuboid-to-columnar epithelium with a thin fibromuscular wall.


Microscopic, adenomatoid cysts which are grossly a solid mass without clear cyst formation.


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


  • Surgical resection of the involved lobe in symptomatic patients


  • 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


  • 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

congenital cystic adenomatoid malformation CCAM

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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Congenital Cystic Adenomatoid Malformation. Gerald Mandell, MD. eMedicine