Malignant fibrous histiocytoma—pleomorphic sarcoma, NOS gene expression, histology, and clinical course. A pilot study
BACKGROUND Little information is available regarding the expression of platelet-derived growth factor (PDGF) isoforms and their receptors in soft tissue malignant fibrous histiocytoma (MFH). MATERIALS AND METHODS We investigated expression of PDGF isoforms and their receptors (PDGF-R alpha and -R beta) in 43 MFH tissue specimens using immunohistochemical techniques. Furthermore, we examined the correlation of PDGF expression in MFHs with proliferative activity assessed by MIB-1 immunohistochemical staining. RESULTS Positive cytoplasmic immunoreactivity for PDGF-AA, -BB and -AB was identified in tumor cells of 28 (66%), 4 (10%) and 26 (61%), respectively, of the 43 MFHs analyzed. Positive cytoplasmic immunoreactivity for PDGF-R alpha and -R beta was identified in tumor cells of 41 (95%) and 32 (74%), respectively, of the MFHs. Thirty-four (79%) MFHs coexpressed one or more PDGF isoforms and their corresponding receptors. In PDGF-AA immunostaining, MIB-indices in the high immunoreactivity group (> 10% of tumor cells) were significantly higher than those in the low immunoreactivity group (< 10% of tumor cells) (p = 0.031). CONCLUSION Our data provide evidence to support the presence of an autocrine/paracrine mechanism of proliferation control involving the PDGF ligand/receptor system in human MFHs.