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[The clinicopathological features of early renal amyloidosis]
Su-xia Wang1, Wan-zhong Zou, Mei Wang
1Department of Electron Microscopy, Peking University First Hospital, Beijing 100034, China.
Objective:
To investigate the clinicopathological manifestations of early renal amyloidosis (AL) and its diagnostic criteria.
Methods:
Fifteen cases with early renal amyloidosis admitted from 1994 to 2001 were collected from the hospital, and their clinical and pathological features were reviewed. Of them, the initial diagnoses were not made by depending findings from the light microscopy (LM) and immunofluorescense (IF), but confirmed by electron microscopy (EM) afterwards. Immuno-electron microscopy (IEM) were applied for amyloidosis typing.
Results:
Most patients of early renal AL were in the middle to old age. Nephrotic syndrome was the most prominent symptoms and signs accompanying with rare microscopic hematuria and hypertension. Most of them had a normal renal function. Pathological examinations of renal biopsies using LM and IF showed mild mesangial proliferation and mild thickening of glomerular basement membrane (GBM). Immunoglobulins and complements were negative or only scanty in certain cases, but in all cases there was a light chain protein deposition homogeously. There were 4 cases of minimal change glomerulopathy, 5 cases of mild mesangial proliferative glomerulonephritis, 5 cases of stage I membranous nephropathy, and 1 case of cast nephropathy diagnosed with LM. The amyloid fibrils (diameter 8 - 10 nm) were randomly distributed in the mesangium, along GBM and at the arteriolar wall under EM. Additionally, Congo red staining was positive. IEM demonstrated that amyloid fibrils labeled with colloid gold was combined with a kind of light chain protein which was confirmed as the light chain type of AL.
Conclusions:
The diagnosis of early renal AL was occasionally neglected by depending only findings of LM and LF. However, special amyloid fibrils can be detected using EM. EM observation is an indispensable technique for the diagnosis of early renal AL and the typing of AL may further be determined by using IEM.
Insights
Early renal amyloidosis (AL) often presents with nephrotic syndrome. Electron microscopy (EM) is crucial for diagnosing early renal AL, detecting characteristic amyloid fibrils, and typing amyloidosis using immuno-electron microscopy (IEM).
Area of Science:
- Nephrology
- Pathology
- Immunology
Context:
- Early renal amyloidosis (AL) diagnosis is challenging with conventional methods.
- Light microscopy (LM) and immunofluorescence (IF) may not detect subtle early changes.
- Electron microscopy (EM) offers superior resolution for identifying amyloid deposits.
Purpose:
- To investigate the clinicopathological manifestations of early renal amyloidosis (AL).
- To establish reliable diagnostic criteria for early renal AL.
- To evaluate the utility of EM and immuno-electron microscopy (IEM) in diagnosis and typing.
Summary:
- Fifteen early renal AL cases were analyzed for clinical and pathological features.
- LM/IF showed mild mesangial proliferation and GBM thickening; light chain deposition was key.
- EM identified characteristic amyloid fibrils, and IEM confirmed light chain type AL.
Impact:
- Highlights the limitations of LM/IF in early renal AL diagnosis.
- Emphasizes EM as an indispensable tool for accurate diagnosis.
- Demonstrates IEM's role in precise amyloidosis typing, guiding treatment.