Major anomalies are less frequent in the respiratory system than in the kidneys, genital organs or digestive tract. In over 10,000 necropsies at the New York Hospital, including many performed on newborn infants, there has been no previous instance of absence of a lung. Ellis1 stated that Théremin found 2 cases in the records of 30,000 autopsies performed at a foundling hospital. Schmit2 and Allen and Affelbach3 reported fetuses with absence of both lungs, but this condition seems exceptionally rare and is of course of no clinical significance.
Deficiency of a lung has been classified as of three types by Schneider.4 In type 1, there is no trace of a bronchus—true aplasia of the lung and bronchus. In type 2, the bronchus is represented by a blind pouch or a nodule of cartilage and fibrous tissue and there is no pulmonary tissue—aplasia of the lung. In