Ultrastructural analysis of renal arteriolopathies in glomerular and tubulointerstitial diseases.

This communication describes the electron microscopy (EM) study of the small arterial vessels in renal biopsies from 32 patients with a variety of glomerular and tubulointerstitial diseases. With the possible exception of lipoid nephrosis, all types of glomerular and tubulointerstitial diseases were associated with abnormal arterial vessels. The vascular abnormalities included variable thickening and irregularity of the basement membranes (sclerosis), excessive elastic tissue and collagen fibers, atrophic or necrotic smooth muscle cells, and electron-dense deposits. The EM of glomeruli and tubules from the same biopsy specimens often revealed similar features, i.e., sclerosis, necrotic changes and electron-dense deposits. The pathogenesis of the arteriolopathies, like that in many glomerular and tubulointerstitial diseases, remains unclear. Hypertension was considered a factor, but only 15 percent of the patients were hypertensive. Furthermore, vascular lesions in patients with hypertension were no worse than those without it. Whatever may be the pathogenesis of these arteriolopathies, the similarities between the renal arteriolar and glomerular abnormalities and between arteriolar and tubular lesions suggest a common mechanism of inducement of the lesions.