A general model for the light and electron microscopic morphometry/stereology (M & S) of precancerous epithelial transformation using clinical biopsies.

A morphometric model is presented which has proved valuable in the analysis of precancerous lesions at the light and electron microscopic level. The material consisted of biopsies of nasal mucosa embedded in plastic and sectioned perpendicular to the luminal surface. Sampling was restricted to the basal layer in order to compare in the different metaplastic and dysplastic stages a common cell type which is easy to identify in all stages and to reduce the workload. The application of digitizers, classical point counting procedures and linear parameters all allow a good separation between the different types of epithelium. The latter method is especially advisable in diagnostic pathology since the workload becomes drastically reduced as a consequence of linear instead of area parameters (e.g. cell width, i.e. contract zone with basement membrane, instead of cell size) and classifying instead of counting points. A 3-class ruler served for the estimation of the transverse diameters of nuclei, cell width and the sum of the longitudinal and transverse nucleolar axes. The use of a weighted index is more sensitive than simple measurements. The reliability of the method was also tested in a prospective study in which the biopsies were first analyzed by morphometry. The agreement between the prior morphometric classification and the subsequent histologic classification was 91%. The results demonstrate that basal cells alone carry the information for grading metaplastic and dysplastic changes in epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)