[Pathological changes and pathogenesis of chronic lung diseases in infants]

Chronic lung disease (CLD) in infants was studied in 50 autopsy cases clinicopathologically. These cases were divided into three groups clinically. Pathological changes in the lung were similar among these three groups. Changes of elastic fibers in the alveolar septum were characteristic; irregular and unevenly distributed elastic fibers were found in the majority of CLD cases. The abnormally distributed elastic fibers could contribute to occurrence of focal emphysema. The lungs from 5 special cases were devoid of elastic fibers in the alveolar septum. In such cases, abnormality of elastin production by fibroblasts or abnormal interaction between protease and anti-protease was hypothesize as the mechanism of occurrence. The relationship to adult lung diseases was also discussed.