TYPE I CYSTIC ADENOMATOID MALFORMATION

• Single cyst or more commonly multiple cysts (>2 cm) within the hemithorax.
• Cysts may involve an entire pulmonary lobe.
• Cysts are clustered with one or more 2-10 cm cyst(s) surrounded by multiple smaller cysts.
• The larger cysts contain respiratory epithelium whereas the smaller ones resemble dilated bronchioles (1).
• Most frequent type (75%), and 75% are right sided.
• Mediastinal shift in about 80%.
• Survival rate is high (90%).

Postnatal chest X-ray
Postnatal barium studies – needed to exclude a right sided diaphragmatic hernia. Note the normal position of the stomach and small and large intestines

DIFFERENTIAL DIAGNOSIS

1. The multiple large cysts differentiate bit from a bronchogenic cyst which is small, solitary and situated near the midline.
2. The delicate internal septations distinguish Type I CAML from a duplication cyst.

REFERENCES

1. Rosada-de-Christenson ML, Stoker JT. Congenital cystic adenomatoid malformation. Radiographics 1991;11:865-866.