Idiopathic nodular glomerulosclerosis: three Japanese cases and review of the literature.

Idiopathic nodular glomerulosclerosis (ING) is characterized as diffuse nodular glomerulosclerotic lesions, closely resembling Kimmelstiel-Wilson lesions without diabetic mellitus. We report here three Japanese cases of ING and discuss the previous reports. The patients were 75-, 48- and 84-year-old males with a history of long-term hypertension. Laboratory examination revealed moderate proteinuria and mild renal dysfunction. Diabetes mellitus was excluded by repeated clinical and laboratory investigations. Renal histology revealed nodular glomerulosclerosis, and both afferent and efferent arteriolosclerosis in all patients. In electron microscopy, the glomerular basement membrane was markedly thick in all patients. A low-protein diet and potent anti-hypertensive treatment using angiotensin-converting enzyme inhibitors were initiated in all patients and urinary protein excretion significantly reduced without the progression of renal dysfunction. We reviewed 42 previously reported cases and our three cases. The analysis revealed that common clinical features of ING are being male (82.2%) of relatively advanced age (mean age 61.3 years), with hypertension (82.2%), mild renal dysfunction (mean serum creatinine 2.9 mg/dl) and moderate urinary protein excretion (mean 4.05 g/day). Common histopathological findings of ING are nodular glomerulosclerosis (100%), arterio-arteriolosclerosis (91.2 and 89.7%) and glomerular basement membrane thickening (85.7%). In conclusion, ING is one of the phenotypes of arteriosclerotic renal disease without diabetes mellitus. Severe arterio-arteriolosclerosis may contribute to the progression to glomerular nodular formation in ING. The combination of renin-angiotensin system inhibition and a low protein diet can be beneficial for the reduction of urinary protein excretion.