Immunohistochemical study of the expression of matrix metalloproteinase-9 in skin lesions of mycosis fungoides.

Matrix metalloproteinase-9 (MMP-9) has been correlated with poor clinical outcome in various malignancies and is associated with enhanced tumor growth and dissemination through its role in angiogenesis. This study was carried out to review the immunohistological staining of MMP-9 in skin lesions of different stages of mycosis fungoides (MF). The study was carried on 22 patients with MF and 10 healthy controls. Immunohistochemical staining using MMP-9 monoclonal anti-human antibodies was performed to determine the intensity of expression and distribution pattern of MMP-9 in MF lesions and in normal control skin. The general intensity of expression of MMP-9 was found to be significantly higher in cases with MF than in controls, and it increased in direct proportion to the increase in disease severity, being greatest in the tumor stages. A significantly greater number of blood vessels were found in cases with MF when compared with controls, and the MMP-9 expression by endothelial cells was significantly higher in endothelial cells within tumor cell aggregates than in endothelial cells outside the tumor cell aggregates. This study raises the possibility that MMP-9 may play an important role in the development of MF lesions, and its significantly higher expression in tumor stages may point to a possible role in disease progression. Further studies are needed to validate these findings and to assess the possible therapeutic role of drugs targeting MMP-9 in the treatment of MF.