Five cases of congenital lung cyst.

More than 150 cases of congenital lung cyst have been reported in the literature. In the majority the cysts were multiple and only about 14 cases have been described in which a large single cyst was present. There is considerable diversity of opinion regarding the aetiology of the condition. Some have attributed it to developmental abnormalities such as faulty development of the lymph vessels of the corresponding lung lobes leading to hydropic cystic formation (Grawitzl) or defective development of alveoli with widening of bronchi2, some to congenital atelectasis3 and some to inflammatory processes such as bronchopneumonia4' 5 or congenital syphilis. Koontz6 describes a case in which there was narrowing of the smaller bronchi from over-growth of the lung epithelium with dilatation of the bronchial system distal to the obstruction. It appears, therefore, that some attribute the condition to congenital maldevelopment and others to disease affecting the lung or bronchi either in utero or after birth. It is probable that in most of the cases the cysts derive their origin from bronchial or atrial tissue. Histologically the walls of the cysts have usually been found to be lined with columnar or cuboidal epithelium and the walls to contain unstriped muscle, elastic and fibrous tissue and sometimes cartilage. In some cases flattened epithelium has been found. In a case reported by de Lange' in which there were numerous cysts, the smallest were lined by cylindrical epithelium, the larger by cuboidal or flat epithelium and in the largest the walls were almost completely denuded of epithelium. Stewart, Kennedy and James7 reported similar findings in their case of multiple cysts. The presence of flattened epithelium does not necessarily exclude the possibility of a cyst being derived from bronchial or atrial tissue for the nature of the epithelial lining may be profoundly modified by ballooning of the walls of the cyst and by the presence of infection. Koontz6 has collected the cases recorded up to 1925 and discussed the aetiology, and Anspach and Wolman have added 2 additional cases of solitary cyst and reviewed the literature up to 1932. Since then I have been able to find reports of 5 cases of solitary cyst. Three contained air9 10 ll, one fluid and air (Croswell and King12) and one pus (Zarfl'3). Three died but in only one was there a post-mortem examination (Gammon and Mallory'0). In this case the cyst, which contained air and was connected with a bronchus by a small opening, had ruptured into the pleura. The wall of the cyst was trabeculated and was denuded of epithelial lining. The case