Expression of S100A2 and S100B proteins in epithelial tumors of the skin

Background: The purpose of this study was to evaluate the expression of Ca2+-binding S100 proteins, S100A2 and S100B, in normal skin. These immunohistochemical stain patterns were compared with those in a variety of epithelial tumors. Methods: Paraffin-embedded tissues of 38 skin tumors were evaluated immunohistochemically with S100A2 and S100B antibodies. Results: Epidermal basal cells, epithelial cells of sebaceous glands, hair follicle epithelia, and eccrine ducts reacted strongly with S100A2 antibody. Langerhans' cells and melanocytes were labeled by S100B. Varying types of skin appendage tumors and most peripheral cells in tumor nests of basal cell carcinoma and squamous cell carcinoma showed positive S100A2 immunoreactivity in neoplastic cells. Basophilic cells of calcifying epithelioma were occasionally stained with S100A2 antibody. Chondroid syringoma containing neoplastic myoepithelial cells stained strongly for both S100A2 and S100B. Conclusions: We conclude that S100A2 can be a specific marker of epithelial cells in the different skin tumors. However, these antibodies are not of much help in classifying skin appendage tumors.