LearningRadiology - Cystic Adenomatoid Malformation

• Form of pulmonary hamartoma occurring in utero between 4-10th week

• Most often found in infants, sometimes adults

• No lobar preference

• Solid in infants, more cystic in children

• Do communicate with the tracheobronchial tree (DDx from intralobar sequestration which usually don’t))

• Supplied by pulmonary circulation

Types

Type 1 (50%) — single or multiple large cysts — excellent prognosis following resection
Type 2 (40%) — Multiple cysts < 12 mm — poor prognosis 2° associated congenital anomalies
Type 3 (10%) — solitary mass with microscopic cysts — poor prognosis 2° hypoplasia of lung

X-ray

• Unilateral mass with well-defined margins and numerous air-containing cysts

• Space occupying so expect shift of heart and mediastinum away from lesion

• May occasionally present as solid mass which evolves into cystic mass

• DDX – Sequestration, diaphragmatic hernia or rupture, congenital lobar emphysema

• On fetal US, look for fetal ascites and polyhydramnios

Clinically

• May be cyanotic; usually symptomatic during first days of life