FIBROSING VASCULITIS IN WEGENERS GRANULOMATOSIS - ULTRASTRUCTURAL ANDIMMUNOHISTOCHEMICAL ANALYSIS OF THE VASCULAR-LESIONS

This study of two cases of pulmonary Wegener's granulomatosis (WG) foc uses on the ultrastructural aspects of the vascular wall injury and on the immunohistochemical characterization of the perivascular connecti ve matrix. The iterative waves of endothelial cell necrosis and regene ration are demonstrated by the multilamellar appearance of the basal l amina. Neutrophils infiltrate the vessel wall and myofibroblasts are r ecruited to injured vessels. The perivascular connective matrix associ ates basement-membrane like and fibrillar material with fibrin deposit s. The initiation of the fibrosing process was assessed by the visuali zation of matrix molecules involved in targeting (p-fibronectin), orga nizing (cellular fibronectin and tenascin) and stabilizing (lysyl-oxid ase) the fibrogenic activity. These elementary lesions affect differen t levels of the vascular tree, and capillaritis is involved in the ext ension of the pathological process. Lysyl-oxidase labelling reveals th e fibrosing front which is located on the border of dense fibrosis. Th e markers of fibrosing activity disappear in the areas of fibrosis fol lowing vasculitis and/or ischaemic necrosis and/or granulomatosis. Vas culitis plays a major role in both the genesis and progression of the fibrosis observed in the late stage of WG.