THE PATHOLOGY OF ACUTE BRONCHIOLITIS—A STUDY OF ITS EVOLUTION

Abstract

Summary The histology of the repair phase of bronchiolitis is presented. Evidence of old inflammatory damage to bronchioles was found in all lungs examined, except those of new‐born infants. These changes were minimal in macroscopically normal lungs, and in these were more obvious in older patients than in the young. In the lungs in which macroscopic structural changes such as bronchiectasis, emphysema and scarring were present, bronchiolar damage was much more extensive. In all examples maximal changes were found in the region of the terminal bronchiole. The evolution of these lesions was studied by observations on early changes, and the origin of some of the types of damage is suggested. Complete obliteration of bronchioles was common, but not easily discernible. The factors influencing the ease with which the changes can be recognized are discussed, and it is concluded that such changes are much more common than has previously been indicated.