Renal pathology in diabetes mellitus - abstract

Shah, Dipak J

ABSTRACT

The morphological changes in both insulin-dependent and non-insulin-dependent diabetes mellitus (IDDM and NIDDM) are indistinguishable. The earliest pathological changes are enlarged glomeruli due to hypertrophy seen mainly in IDDM patients. There is also an increase in total volume of both basement membrane (BM) and capillary lumen. A second peak of glomerular hypertrophy occurs late in the disease when overt pathological changes are established. At this, many glomeruli are comprised and the open, functioning glomerulii will show a three-fold increase in size. The pathognomonic change in diabetic nephropathy is nodular glomerulosclerosis or nodular intercapillary glomerulosclerosis (Kimmelstiel-Wilson lesion) which is characterised by enlargement of mesangium due to increase in mesangial matrix. This is associated with diffuse thickening of the capillary wall which is due to increased BM material. A diffuse lesion may be considered specific after ruling out all the other causes of thickened BM, i.e. immune-complex glomerulonephritis, anti-glomerular basement membrane antibody disease, etc. The exudative and capsular drop lesions are not specific for diabetes mellitus but can be considered to be highly suggestive lesions. There is hyaline arteriolosclerosis, involving both afferent and efferent arterioles. The only pathognomonic tubular lesion (Armanni-Ebstein lesion) is a rare finding, and is found in the straight portion of the proximal convoluted tubules in which tubular cells contain glycogen. The patients with the nephropathic syndrome may show lipid-filled proximal tubules. In the late stages, there are non-specific atrophic changes with thickening of the basement membrane. There are no specific gross features of the kidney in diabetes mellitus. It may be enlarged, normal or granular contracted. The subscapular surface may either be finely or coarsely granular with focal depressed scars. The cut surface may show thinning of the cortex, loss of the corticomedullary junction and prominent blood vessels. Papillary necrosis is uncommon (AU)