Studies in oral leukoplakias: XI. Histopathology of Leukoplakias in Indians Chewing “Pan” With Tobacco

Abstract

Quantitative determinations were made in a group of 22 leukoplakias of the cheek obtained in Bombay, India, from 16 male patients chewing tobacco in pan and in six control specimens. There were no marked differences between group averages, but leukoplakias and controls differed strikingly in the small variability of the controls and the great variability of the leukoplakias. In every quantitative trait, at least one third of the leukoplakias and usually the great majority had values below and above the probable range containing 99 % of controls.

Leukoplakias with atrophic and with thick epithelium averaged similar spacing and relative height of connective tissue papillae. In the thin group the length of the basal layer relative to that of the surface was one half that in the thick group. The number of mitoses per 100 μ basal layer was the same in both groups, but the number per 100 μ surface was twice as high in the thick group. Mitotic activity according to both measures averaged higher values in both groups of leukoplakias than in the controls. Mitotic activity of individual leukoplakias correlated poorly with epithelial thickness and well with the relative length of the basal layer.

All leukoplakias showed frank keratinization or semikeratinization. In every keratinized specimen, both para- and orthokeratin were present. Nearly no dividing cells were present in specimens with orthokeratin layers of 30 % or more of the total epithelial thickness. Semikeratinized specimens resembled keratinized specimens in the deeper cell layers, but non-keratinized epithelium in the outer part.

Keratinizing traits declined with marked intra-epithelial reaction to inflammation but persisted against all degrees of inflammation in the lamina propria. Inflammation and intra-epithelial edema were more than twice as marked in the atrophic group, but the density of migrating inflammatory cells was the same in both groups of leukoplakias. Leukoplakias of both groups came from patients of similar age and fairly similar duration of the chewing habit. However, the daily exposure time to tobacco in pan was, on the average, twice as long in the patients with atrophic epithelium.