Increased fibroblast density in actinic cheilitis: Association with tryptase-positive mast cells, actinic elastosis and epithelial p53 and COX-2 expression

Background: Actinic cheilitis (AC) is characterized by epithelial and connective tissue alterations caused by ultraviolet sunlight overexposure known as photodamage. Fibroblasts have been linked to photodamage and tumor progression during skin carcinogenesis; however, their role in early lip carcinogenesis remains unknown. The aim of this study was to assess the density of fibroblasts in AC and normal lip (NL) samples and determine their association with markers of lip photodamage. Methods: Fibroblasts, mast cells, p53, COX-2, and elastin were detected in NL (n=20) and AC (n=28) biopsies using immunohistochemistry/histochemistry. Mast cell and fibroblast density and epithelial p53 and COX-2 expression scores were then obtained. Elastosis was scored 1-4 according to elastin fiber density and tortuosity. Results: Fibroblasts, mast cells, p53, COX-2, and elastosis were increased in AC as compared to NL (P<0.001). Multivariate analysis showed an association between fibroblast and mast cell density at the papillary and reticular areas of AC and NL (P<0.05). Papillary fibroblast density was also associated with epithelial p53 and COX-2 expression (P<0.05). Increased fibroblast density, both papillary and reticular, was found in the high elastosis group (scores 3-4) as compared to the low elastosis group (scores 1-2) (P<0.01). Increased reticular mast cell density was detected only in the high elastosis group (P<0.01). Conclusions: Fibroblasts are increased in AC, and they are associated with mast cell density, epithelial p53 and COX-2 expression, and actinic elastosis. Therefore, fibroblasts may contribute to lip photodamage and could be considered useful markers of early lip carcinogenesis.