Table 1 Stocker classification of congenital cystic adenomatoid malformation [4, 5, 8]

0

1–3%

Solid appearance with small and firm lungs

Tracheobronchial origin. Microscopically shows bronchiolar type airway with cartilage, smooth muscle, and glands separated by abundant mesenchymal tissue.

Differential diagnosis: bronchogenic cyst

1

50–70%

Single or multiple large cysts (> 2 cm)

Wall contains flattened, cuboidal cells. It also contains prominent smooth muscle and elastic tissue. Sometime mucus producing cells are seen and presence of cartilage is very rare

Contralateral mediastinal shift

2

15–30%

Multiple small cysts (< 2 cm)

Cyst wall lined by ciliated cuboidal to columnar epithelium that resembles respiratory bronchioles. Distended alveoli are present between the epithelium lined cyst. Mucus cells and cartilage are not seen.

Systemic anomalies like Bilateral renal agenesis, abdominal wall defects, hydrocephalus, spinal deformities, diaphragmatic hernia, jejunal atersia, tracheoesophageal fistula, imperforate anus, ventriculoseptal defects, tetralogy of Fallot, truncus arteriosis, and sirenomelia

3

5–10%

Bulky non-cystic lesions

Bronchial-like structures are lined by ciliated cuboidal epithelium and separated by masses of alveolus-sized structures by non-ciliated cuboidal epithelium .

Contralateral mediastinal shift.

Rarely associated with esophageal cyst.

4

10–15%

Distal acinar origin. Large cysts (> 10 cm) lined by flattened epithelium and resting on loose mesenchymal tissue

Differential diagnosis: pulmonary blastoma