Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) are benign and intermediate malignant fibrotic dermal tumours, respectively. The contribution of transforming growth factor (TGF)-β has been implicated in the progression of sclerosis in fibrotic diseases.Objectives
To investigate the expression of TGF-β receptors in these fibrotic tumours.Methods
We examined the expression levels of TGF-β type I and type II receptors (TGFβ-RI and TGFβ-RII) in DF and DFSP using in situ hybridization and immunohistochemical analysis. We also examined the expression of TGF-β1 and collagen type I using immunohistochemical analysis.Results
We detected strong expression of TGFβ-RI and TGFβ-RII on epidermis and epidermal appendages, moderate expression in vascular endothelial cells, smooth muscle cells and neural tissues, and weak expression in fibroblasts in normal skin sections. The expression levels of TGFβ-RI and TGFβ-RII were elevated in the tissue sections of DF in comparison with normal dermal sections using in situ hybridization and immunohistochemical staining. Furthermore, the expression of TGFβ-RI and TGFβ-RII was strong in spindle-shaped cells around DF. The expression of TGFβ-RI and TGFβ-RII was decreased in DFSP in comparison with DF, and their expression was found to be homogeneous in each DFSP tumour cell. The staining for TGF-β1 was found prominently on matrix and spindle-shaped tumour cells of DF, and peripheral regions of DFSP. Weak expression of TGF-β1 was found on normal skin or tumour cells in the central part of DFSP. Type I collagen expression was found on spindle-shaped tumour cells in DF, but not in tumour cells of DFSP.Conclusions
These results suggest the possibility that TGF-β signalling may contribute to the fibrosis around DF, and that TGF-β receptors may play important roles in TGF-β signalling. The expression patterns of TGFβ-RI and TGFβ-RII may be helpful in distinguishing these diseases.