offibrosis, ten differed from the normal and emphysematous lungs by a homogeneous dilatation of the airspaces, in excess of the dimensions predicted on the basis of age. Study of the standard deviations of the mean

ofexcised human lungs obtained at autopsy, the parenchyma and peripheral airways were examined by means of mor. phometric techniques. Among the 30 lungs characterized by the absence offibrosis, ten differed from the normal and emphysematous lungs by a homogeneous dilatation of the airspaces, in excess of the dimensions predicted on the basis of age. Study of the standard deviations of the mean linear intercepts showed that the airspace dilatation was more regular than in emphysematous lungs; in addition, there was no clear-cut destruction, as estimated from the number of alveolar attachments. These lungs were char acterized in addition by an increased thickening of alveolar septa, without inflammation or fibrosis, normal size of the diameter, and reduced density of the membranous bron chioles. Since these lungs were from people older than 60 years, it is assumed that they represent cases of exaggerated airspace enlargement of the aging lung, differing from emphysema by the absence of destruction of alveolar walls. The term “¿ senile lung― is proposed for this condition. (Chest 1992; 101:793-99)