Fig. 3.

Limited cutaneous systemic sclerosis (lcSSc) 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, B, D, G, I) and epithelial cells of sebaceous (D and G) and sweat (F and H) glands are c-kit-immunoreactive. (A–F) Early lcSSc skin. Telocytes are absent from the papillary dermis (A, B, D, double asterisks) and patchily reduced in the reticular dermis. In the reticular dermis, most telocytes are enlarged in shape (C). Telocytes are present around arterioles (E, arrow), nerves (E, arrowhead), hair follicles and sebaceous glands (D, arrows), and eccrine sweat glands (F). (G–I) Advanced lcSSc skin. Telocytes are absent from the papillary dermis and severely reduced in the reticular dermis and around most of the adnexal structures (G). In the deep reticular dermis, telocytes are preserved around sweat glands (H). A normal distribution of telocytes is observed in clinically non-involved lcSSc skin (I). (J–L) Advanced lcSSc skin, double immunofluorescence labelling for CD34 (green) and CD90/Thy-1 (red). Very few telocytes are observed (J and L). Fibroblasts are CD90-positive/CD34-negative (K, L, arrows). A CD90-positive vascular wall-resident stem cell niche is scarcely surrounded by telocytes (L, arrowheads). Scale bars are indicated in each panel.