Impaired expression of stem cell factor in dermatofibroma fibroblasts

The number of mast cells is increased in dermatofibroma lesions and plays a role in the induction of fibrosis or its proliferation. We have investigated stem cell factor expression in solitary and multiple dermatofibromas by immunohistochemical straining. We also analyzed messenger RNA (mRNA) expression of stem cell factor in dermatofibroma tissues and cultured fibroblasts derived from dermatofibromas, using reverse transcriptase polymerase chain reaction. We found immunoreactive stem cell factor in keratinocytes, dermal fibroblasts, melanocytes and hair follicles. Unexpectedly, a reduced expression of immunoreactive stem cell factor in dermatofibroma fibroblasts was observed in solitary and multiple type. However, mRNA expression of stem cell factor was detected both in the dermatofibroma tissue and cultured dermatofibroma-derived fibroblasts. We speculate that the altered expression of stem cell factor of tumor cells in dermatofibroma lesions can be associated with the tumor cell proliferation and induction of dermatofibroma.