ABSTRACT
Pulmonary agenesis is associated with failure of respiratory development beyond the carina. Bilateral pulmonary agenesis results when this occurs at the stage of the single respiratory bud in the embryonic phase. If the bud develops on one side only, unilateral pulmonary agenesis occurs (Figure 32.1) and the trachea runs into a sole bronchus with no carina. If an airway ‘stump’ is present, then the condition is called pulmonary aplasia. The pulmonary artery is always absent and there is agenesis of both sympathetic and parasympathetic plexuses with usually a lack of parietal pleura.27 Lesions occur on the left in 70 percent of cases and equally in males and females. Lobar agenesis and aplasia are rarer than complete absence of one lung and usually affect the right upper and middle lobes together.51,99
Pulmonary agenesis has been observed in monozygotic twins51 and in rats after the mother was deprived of vitamin A.124 Bilateral pulmonary agenesis is extremely rare and may occur in association with anencephaly.88
