Stiff skin syndrome: evidence for an inflammation-independent fibrosis?

OBJECTIVES: Stiff skin syndrome (SSS) is a rare scleroderma-like syndrome of unknown aetiology. A 16-year-old boy presented with thoracic and abdominal asymmetry, and 'orange peel' cutaneous lesions, with fibrotic stone-hard indurations at the buttocks, thighs and arms leading to secondary joint contractures of the extremities. Our aim was to analyse the expression of extracellular matrix (ECM) molecules and pro-fibrotic cytokines in the dermis and epidermis of SSS. METHODS: The diagnosis of SSS was confirmed by clinical and histopathological examination. Collagen type 1 alpha-2 chain (Col1A2), fibronectin-1, thrombospondin-1, TGF-beta, connective tissue growth factor (CTGF), IL-6, -1beta, ET-1, Fibroblast growth factor receptor 3 (FGFR-3) and MCP-1 expression was analysed in SSS and age- and sex-matched healthy control skin by real-time PCR. VEGF expression was also studied. RESULTS: Histopathological examination showed flattened dermal papillae, a scarce presence of sub-epidermal microvessels and mild dermal fibrosis, but no inflammatory infiltrates. In the SSS dermis, the expression of IL-1beta, -6 and MCP-1 was low, whereas VEGF was intensively expressed. No differences were observed for TGF-beta, CTGF and ET-1. In contrast, col1A2, fibronectin-1 and thrombospondin-1 were overexpressed in the SSS dermis. CONCLUSION: In our SSS patient, an overexpression of ECM proteins was detected, whereas no inflammatory infiltrates or up-regulation of pro-fibrotic cytokines were found. The data suggest that fibrosis in SSS might be independent from inflammation.