Quantification of melanocytes in sun-damaged skin.

Abstract

The density of melanocytes varies by anatomic site and degree of sun damage. To determine the density of melanocytes and frequency of confluence in specimens adjacent to nonmelanoma skin cancers. Two hundred final layer specimens from Mohs surgery for basal cell carcinomas were analyzed by using MART-1. Data for 162 skin specimens from the head demonstrated an average keratinocyte to melanocyte ratio of 7.12 and 8.19 for epidermis and adnexal structures, respectively. The 23 specimens from the trunk demonstrated respective ratios of 7.54 and 7.46, and 13 specimens from extremities demonstrated ratios of 8.69 and 12.38. Margins from Mohs micrographic surgery for nonmelanoma skin cancers were utilized as a proxy for chronically sun-damaged skin. Our results suggest that chronically sun-exposed skin demonstrates increased melanocytic density, but confluence of melanocytes is rare. Occasionally intraepidermal pagetoid scatter and isolated melanocytic nests were rarely noted. These findings alone should not support an unequivocal diagnosis of melanoma in situ.