Har-Shai, Y., Departments of Plastic Surgery, Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
Mettanes, I., Departments of Plastic Surgery, Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
Zilberstein, Y., Sackler Cellular and Molecular Imaging Center (SCMIC), Tel Aviv University, Tel Aviv, Israel
Genin, O., Institute of Animal Sciences, Volcani Center, Bet Dagan, Israel
Spector, I., Institute of Animal Sciences, Volcani Center, Bet Dagan, Israel
Pines, M., Institute of Animal Sciences, Volcani Center, Bet Dagan, Israel

Background Keloid presents a great healthcare challenge. The patients suffer from aesthetic disfiguration and occasionally from pruritus, pain and discomfort. Although various treatments are recommended, a single, highly effective treatment represents a great clinical need. Objective The cellular events and histopathology that follow intralesional cryosurgery were evaluated including cell proliferation, the number of cells expressing fibroblast markers, collagen synthesis and organization and mast cell infiltration. Methods Biopsies were collected before and after intralesional cryoneedle procedure. Collagen structure was evaluated with confocal microscopy. Mast cells, blood vessels and cell proliferation were evaluated using immunohistochemistry. Results Keloids contain abnormally thick collagen bundles, organized in swirls comprising closely bound fibrils. After intralesional cryosurgery, the collagen bundles lost their swirl structure, the thickness of the collagen layer decreased, and the bundles became more compact with less space between the fibres. A clear distinct transition zone separated the treated from the unaffected area. The frozen tissue was devoid of proliferating cells and mast cells whereas the number of blood vessels remained unaltered. Most of the fibroblasts expressed all tested myofibroblast markers although some exclusively expressed one and not the other. Few nuclei were observed in the affected area after treatment and very few of them expressed any fibroblast markers. Conclusions Intralesional cryosurgery resulted in major changes in collagen structure and organization. The treatment reduced the number of proliferating cells, of myofibroblasts and of mast cells. These results may explain the reduction in no-response rate and the amelioration of the clinical symptoms after intralesional cryosurgery treatment. © 2010 European Academy of Dermatology and Venereology. No claim to original US government works.