Role of mast cells in skin tag development: an immunohistochemical study.

Objective: To detect mast cell density by toluidine blue and immunohistochemical staining for mast cell tryptase in skin tags as compared to normal skin to determine whether they have a role in skin tag development.

Study design: This study was carried out on 30 patients with skin tags and 10 age- and sex-matched healthy controls without skin tags.

Results: There was a significant difference between skin tag and control groups regarding mast cell density evaluated by toluidine blue staining (p = 0.003) and mast cell tryptase expression (p = 0.001), where the density was higher in skin tags as compared to normal skin. Mast cells were higher in number using toluidine blue staining in lesions arising in sites other than the head and neck (p = 0.028). High expression of mast cell tryptase was significantly associated with marked collagenosis (p = 0.02) and presence of eosinophils (p = 0.04).

Conclusion: The present study demonstrates the possible role of mast cells in promoting fibrosis and facilitating the development of skin tags. Mast cells may attract eosinophils to cooperate in inducing more fibrosis in skin tag development.