Fig. 4.

Diffuse cutaneous systemic sclerosis (dcSSc) skin, immunohistochemistry. (A–I) Double immunoenzymatic labelling for CD34 and c-kit with horseradish peroxidase (green) and alkaline phosphatase (red) detection systems respectively. Everywhere in the dermis, telocytes and endothelial cells are CD34-positive, mast cells are c-kit-positive. Melanocytes (A–C) and epithelial cells of sebaceous (E and G) and sweat (D and F) glands display c-kit-immunoreactivity. (A–F) Early dcSSc skin. Telocytes are very few or absent in the papillary and reticular dermis (A and B). (C) Some telocytes are observed around a nerve (arrowhead) and microvessels. Telocytes form a single discontinuous layer surrounding hair follicles and sebaceous glands (E, arrows), and eccrine sweat glands (D, arrow and F). (G–I) Advanced dcSSc skin. Telocytes are almost completely absent in the papillary and reticular dermis (G–I), in the connective tissue surrounding skin adnexa (G and I, arrows) and around occluded microvessels (H, arrow). (J–L) Advanced dcSSc skin, double immunofluorescence labelling for CD34 (green) and CD90/Thy-1 (red). Two microvessels display CD34-positive endothelial cells (J and L). Telocytes are not identifiable, while several fibroblasts are present (K and L, arrows). Scale bars are indicated in each panel.