Pulmonary Agenesis and Hypoplasia.

In recent years the more frequent use of x-rays has revealed various congenital abnormalities of the lungs which had formerly passed undetected during life, since the clinical signs and symptoms may be minimal. An attempt is made here to elucidate the different pictures which may be seen in varying degrees of underdevelopment of the lungs. For clarity of description the following nomenclature is based on Schneider's (1912) classification: AGENESIS of a lung, where there is complete absence of lung and bronchus. APLASIA of a lung, where there is a rudimentary bronchus and no pulmonary alveolar tissue. HYPOPLASIA of a lung or part of a lung, where the alveolar tissue is underdeveloped. The number of cases so far reported in the literature is about fifty. Hurwitz and Stephens (1937) review thirty-four cases and Deweese and Howard (1944) make the list up to forty-four. The majority of these recorded cases are of the first type, viz. agenesis, or complete absence of a lung, more commonly the left lung. The pleura may be partially or completely absent; the former is more common, the pleura then containing the displaced heart and mediastinal structures with some excess fluid. The pulmonary blood-vessels of the affected side are usually absent. The remaining casereports describe severe degrees of aplasia or hypoplasia with practically no functional lung tissue; it is therefore of interest to report cases 4 and 5 where there is only partial underdevelopment of one lung associated with an anatomical abnormality of the bronchial tree, all of which complex appears to be a permanent abnormality. In contrast, cases 6 to 11 show a similar underdevelopment of one lung at birth, but the condition slowly readjusts itself to normal in two to three years. The majority of recorded cases of maldevelopment have been in young infants diagnosed shortly before death or at autopsy, but the condition is compatible with a full span of life, as in a female who lived to seventy-two years. The sex incidence has been about equal. The common association of other congenital abnormalities in the chest or elsewhere is noteworthy. Symptoms varied from case