BACKGROUND: Little information is available on the expression of stem cell factor (SCF) and its receptor c-kit in soft tissue tumors of a fibrohistiocytic origin, including malignant fibrous histiocytoma (MFH). MATERIALS AND METHODS: We investigated the endogenous expression of SCF and c-kit in 43 MFH tissue samples using immunohistochemical techniques. Furthermore, we examined the correlation of SCF expression in MFHs with proliferative activity assessed by mitotic indices and MIB-1 immunohistochemical staining. RESULTS: Positive immunoreactivity for c-kit was identified in tumor cells of only one MFH case, while the remaining 42 cases were negative. In the one positive case, immunohistochemical staining was focal. Positive immunoreactivity for SCF was identified in 31 out of 43 cases studied (72%, focal; 11, moderate; 6, diffuse; 14). There were no significant differences in the MIB-1 and mitotic indices between the SCF-positive and negative groups. CONCLUSION: Our data indicate that any direct autocrine effects of the SCF/c-kit system on cell growth regulation are precluded in most MFH cases studied, but it is speculated that SCF might indirectly influence tumor growth by promoting local neovascularization.
BACKGROUND: Little information is available on the expression of stem cell factor (SCF) and its receptor c-kit in soft tissue tumors of a fibrohistiocytic origin, including malignant fibrous histiocytoma (MFH). MATERIALS AND METHODS: We investigated the endogenous expression of SCF and c-kit in 43 MFH tissue samples using immunohistochemical techniques. Furthermore, we examined the correlation of SCF expression in MFHs with proliferative activity assessed by mitotic indices and MIB-1 immunohistochemical staining. RESULTS: Positive immunoreactivity for c-kit was identified in tumor cells of only one MFH case, while the remaining 42 cases were negative. In the one positive case, immunohistochemical staining was focal. Positive immunoreactivity for SCF was identified in 31 out of 43 cases studied (72%, focal; 11, moderate; 6, diffuse; 14). There were no significant differences in the MIB-1 and mitotic indices between the SCF-positive and negative groups. CONCLUSION: Our data indicate that any direct autocrine effects of the SCF/c-kit system on cell growth regulation are precluded in most MFH cases studied, but it is speculated that SCF might indirectly influence tumor growth by promoting local neovascularization.