A morphologic grading scheme for membranous and respiratory bronchioles.

We describe a system for grading pathologic changes in the small airways. This system consists of determining a score of 0 to 3 using a set of pictorial reference standards for any or all of the following variables: wall inflammation, fibrosis, muscle hypertrophy, pigment deposition, epithelial goblet and squamous metaplasia, and intralumenal macrophages. Grading of this type is much faster and easier than formal morphometric analysis. This system has produced a good correlation with pulmonary function test abnormalities, indicating obstruction in cigarette smokers and has also been used to detect lesions produced by other inhaled agents such as mineral dusts.