Minimal renal amyloidosis with nephrotic syndrome

Two patients older than age 50 years had minimal amyloidosis in association with the nephrotic syndrome. The amyloid deposits in each case were so inconspicuous as to have been initially overlooked, and both biopsy specimens were thought to show minimal glomerular changes. A few, widely scattered, silver-positive, epimembranous spicules were found on reexamination by light microscopy, and Congo red and thioflavin T stains and electron microscopy confirmed the presence of small glomerular amyloid deposits. Both patients have since died of renal failure. In our series of biopsy specimens, amyloidosis was found in 14.2% of patients older than age 50 years presenting with nephrotic syndrome or severe proteinuria, over 1 1/2 times the frequency of minimal-change nephrotic syndrome. We therefore urge careful examination for amyloid deposits of all kidney biopsy specimens with the appearance of minimal-change nephrotic syndrome in older patients. Fluorescence microscopy of Congo red- and thioflavin T-stained sections is very helpful in the detection of small deposits.