Pleura in pneumothorax. Comparison of patients with cystic fibrosis and idiopathic spontaneous pneumothorax.

We studied pleura from patients with cystic fibrosis (CF) in order to define abnormalities that predispose to pneumothorax or are unique to CF. We compared the histology of CF pleura with that of young non-CF adults with "idiopathic" pneumothorax. Both CF and non-CF patients with pneumothorax showed distorted elastic fibers in areas of pleural fibrosis, adhesions, or air "cysts." Following pneumothorax, chronic inflammation, granulation tissue, fibrosis, mesothelial hyperplasia, and reactive eosinophilic pleuritis were also common. Although CF pleura appeared more intensely inflamed, only myxoid connective tissue and vascular proliferation were significantly more frequent in CF. Columnar, vacuolated mesothelial cells (Dunnill lesion) were focally observed only in patients with CF. We conclude that extensive degenerative pleural changes may predispose to pneumothorax in CF and represent a nonspecific response to chronic inflammation.