Electron microscopic observation on dark endothelial cells in erythema nodosum-like lesions of Behçet's disease with ultrastructural X-ray spectroanalysis.

We used electron microscopy and electron microscopic X-ray spectroanalysis to examine the biopsies taken from erythema nodosum-like lesions of 20 patients with Behçet's disease. Electron-dense degenerated endothelial cells were found in the microcirculatory beds of the dermis and subcutaneous fat. However, electron microscopic X-ray spectroanalysis failed to demonstrate the localization of either chlorine or base metals in those degenerated endothelial cells. Moreover, neither in ultrastructurally normal endothelial cells, nor in infiltrating macrophages of erythema nodosum-like lesions the positive deposit of chlorine or base metals could not be detected. The results of this analysis suggest that environmental factors do not play an etiologic role in this disease. Significance of the degeneration of endothelial cells is not clear present.