Fig. 6. – Congenital pulmonary airway malformation type 3. a) The lesion is a solid mass resembling atelectatic parenchyma. Only rarely are small "cysts" seen, probably representing dilated bronchioles. b) The lesion consists entirely of small bronchiole- and alveolar duct-like structures lined with cuboidal epithelium. Note the virtual absence of arterial structures (haematoxylin and eosin stain). J.T. STOCKER, A.N. HUSAIN 10