The Expression of Melanin Pigment and Melanocytes in Basal Cell Carcinoma of Sun-Exposed and Non-Exposed Areas

Chun, Bo Mi; Kim, Chul Woo; Kim, Sang Seok; Kim, Kwang Ho; Cho, Seong Jin

Abstract

BACKGROUND: Basal cell carcinomas (BCCs) are the most commonly encountered skin cancers. In Asian patients, marked pigmentation is frequently observed in BCC lesions. Although many authors have documented the incidence of pigmentation in BCCs, its pathogenesis, especially mechanisms associated with sun exposure, have rarely been studied.
OBJECTIVE
This study aimed to evaluate the expression pattern of melanin pigments and melanocytes in BCCs of sun-exposed and non-exposed areas of skin and investigate the association of ultraviolet radiation with the pigmentation process of BCCs.
METHODS
We examined 30 cases of BCCs occurring in sun-exposed areas of skin, and 8 cases of non-exposed areas of skin, using the Fontana-Masson and MART-1 immunohistochemical methods, with paraffin-embedded sections.
RESULTS
Most melanin was found in tumor nests and surrounding dermal stroma (53.0%) and was superficially (60.0%) or fairly uniformly (33.3%) distributed in BCCs of sun-exposed areas. In all BCCs of sun-exposed areas, melanocytes were found in tumor nodules, not in dermal stroma. When the staining level of BCCs occurring in sun-exposed areas was compared with that of non-exposed areas, BCCs of sun-exposed areas showed significantly increased expression in Fontana-Masson (p<0.001, chi-square test) and MART-1 (7.75+/-4.77 vs 2.08+/-2.68; p=0.001, Mann-Whitney U-test) stains.
CONCLUSION
Our immunohistochemical staining of BCC specimens revealed that ultraviolet radiation is closely associated with the pigmentation process of BCCs. Although accurate mechanisms are not yet established, these findings suggest a basis for the idea that complex phenomenon lead to hyperpigmentation in BCC.