Objective: To carry out a feasibility study for the development of procedures for the objective characterization and grading of solar keratotic skin lesions.
Study design: Imagery from sections of skin shave biopsies from 12 light-skinned individuals were digitized. A minimum of 25 nuclei from a solar keratotic lesion and 25 nuclei from a location in histologically normal appearing skin adjacent to the lesion were recorded for each case. Values of karyometric features were computed, and a discriminant function distinguishing normal nuclei from nuclei exhibiting solar irradiation damage was derived.
Results: Approximately 50% of nuclei in solar keratotic lesions were markedly affected by solar irradiation, but even in biopsies from histologically normal appearing skin, 3-30% of nuclei showed signs of such damage. Nuclei from solar keratotic lesions exhibiting such damage had numerous morphometric and karyometric features commonly found in malignant cells. The state of progression of a solar keratotic lesion can be graded by a plot of proportion of nuclei exhibiting solar damage versus the average discriminant function score of the most affected nuclei. This plot provides a monotonically rising progression curve and a numeric grading score.
Conclusion: Karyometry of nuclei from skin biopsies allows objective assessment of the progression of solar keratotic lesions. Similarity of feature values in nuclei from solar keratotic lesions to those in malignant lesions was noted. The progression curve derived in this study could serve to measure the efficacy of chemopreventive or therapeutic intervention.