[Apthae: histologic, immunofluorescent and immuno--electron microscopy study of their pathogenesis].

The present study was done to elucidate the pathogenesis of aphthae in recurrent oral ulcers and Behcet's disease. Histologically, early stages of aphthae showed a predominantly neutrophil infiltrate and leukocytoclasia in the vessel walls, as well as extravasates of erythrocytes. In later stages, also histiocytes and lymphocytes appeared. By direct immunofluorescence technique, 30 of 34 patients showed perivascular precipitates of C3 and Clq, eight patients in addition, IgM and IgG. Remarkably, band-like fine granular precipitates of C3 were present in the basement membrane zone. By immunoelectronmicroscopy, C3 was demonstrated in fine subendothelial granules of the vessel walls and of the epithelial basement membrane below the lamina densa. There were no fundamental differences between the aphthae of recurrent oral ulcers and Behcet's disease. Our findings indicate, that an immunecomplex vasculitis is involved in the pathogenesis of aphthosis.