range 1–10 cm in size, are thin-walled when distended and lined with a smooth membrane with vascular structures visible beneath the surface. Microscopically, the cysts are lined with ciliated pseudostratified columnar epithelium in polypoid folds with interspersed segments of mucogenic cells iny35% of cases (fig. 4). Fig. 2. – Congenital pulmonary airway malformation type 0. a) Grossly, the lung is firm with a finely nodular surface, reflecting the presence of bronchial structures throughout the lesion. b) The lesion is composed of bronchovascular islands surrounded by loose fibrovascular connective tissue (haematoxylin and eosin stain). J.T. STOCKER, A.N. HUSAIN 6