BONE HEMANGIOENDOTHELIOMA - AN IMMUNOHISTOCHEMICAL STUDY RELATED TO HISTOLOGICAL MALIGNANCY AND PROLIFERATIVE ACTIVITY (NORS)

Aims and background: Forty-four bone hemangioendotheliomas (HEs) of di fferent histological grades were studied to evaluate the expression an d distribution of laminin, type IV collagen, cathepsin G and cathepsin D in cell differentiation and malignancy. Results: In poorly-differen tiated HEs the discontinuous distribution of laminin and type IV colla gen around angioblastic cords, tubes and cavities revealed an irregula r and disorganized basement membrane (BM) architecture corresponding t o an increased cell proliferation and secretion of cathepsin D and cat hepsin G by tumor cells. Conclusions: The mean nucleolar organizer reg ion (NOR) area, as a measure of cell proliferation, was significantly higher in grade 4 malignancies than in lower grades, revealing novel p rognostic parameters.