normal parenchyma (fig. 5). They are composed of multiple small cysts (0.5–1.0 cm diameter) lined with a smooth membrane [3, 9]. Microscopically, the lesion is composed of back-to-back dilated bronchioles separated by irregular alveolar duct-like structures. Small arteries, arterioles and venules are interspersed among the bronchioles. CPAM type 2 may be seen in 50% of extralobar sequestrations [10]. Surgical resection in isolated lesions, including those associated with extralobar sequestration, is frequently successful. In cases with other severe anomalies, survival is dependent upon the severity of the anomalies and the ability to successfully treat them. CPAM type 3 CPAM type 3, the original congenital adenomatoid malformation described in 1949 by Ch’in and Tang [1], is composed of gland-like structures resembling terminal/respiratory bronchioles and alveolar ducts. Clinically, the lesion occurs almost exclusively in males, is associated with maternal polyhydramnios in nearly 80% of cases and may lead to death in utero. Live-born infants Fig. 5. – Congenital pulmonary airway malformation type 2. a) Small cysts (0.5–1.5 cm) blend with normal parenchyma. b) Microscopically, these cysts consist of back-to-back bronchiolar-like structures lined with simple columnar-to-cuboidal epithelial cells (haematoxylin and eosin stain). CLASSIFICATION OF CHILDHOOD CYSTIC LUNG LESIONS 9