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[The early lesions of renal amyloidosis]
1Department of Medicine, Kidney Center, Tokyo Women's Medical College, Japan.
Abstract:
Two patients with minimal amyloid deposition in association with nephrotic syndrome are reported. Since the amyloid deposits in each renal biopsy specimen were inconspicuous, both were first thought to be minimal glomerular changes. A few widely scattered, silver-positive, epimembranous spicules were found on careful reexamination by light microscopy. Congo red stain and electron microscopy confirmed the presence of small glomerular amyloid deposits and amyloid fibrils. Furthermore, immuno-fluorescence microscopy showed partial IgA deposits in the mesangial area and capillary wall. We therefore urge careful examination to detect amyloid deposits of all kidney biopsy specimens of minor glomerular abnormalities, or glomerulonephritis with IgA deposits from elderly patients with nephrotic syndrome. Light microscopy of Congo-red-stained sections and electron microscopy of the fibrillar structure very useful for the detection of small amyloid deposits.
Insights
Minimal amyloid deposition can cause nephrotic syndrome, even with inconspicuous kidney biopsy findings. Careful examination using Congo red stain and electron microscopy is crucial for detecting these small amyloid deposits.
Area of Science:
- Nephrology
- Pathology
- Immunology
Background:
- Nephrotic syndrome can present with varied histopathological findings.
- Amyloidosis is a condition characterized by abnormal protein deposits.
Observation:
- Two patients with nephrotic syndrome showed minimal amyloid deposition on initial renal biopsy.
- Subtle epimembranous spicules were noted on reexamination.
- Congo red staining and electron microscopy confirmed amyloid fibrils.
Findings:
- Small glomerular amyloid deposits were identified in patients with nephrotic syndrome.
- Immunofluorescence revealed partial IgA deposits in the mesangium and capillary walls.
- Amyloid deposits can be overlooked in kidney biopsies with minor glomerular abnormalities.
Implications:
- Emphasizes the importance of meticulous examination of kidney biopsies for subtle amyloidosis.
- Suggests considering amyloidosis in elderly patients with nephrotic syndrome and IgA deposits.
- Highlights the utility of Congo red and electron microscopy in diagnosing early-stage amyloidosis.