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Membranoproliferative glomerulonephritis (MPGN type I) and dense deposit disease (DDD) in children
Abstract:
A review of the histologic findings in 27 patients originally classified as having some form of membranoproliferative glomerulonephritis (MPGN) revealed 13 with MPGN Type I and 14 with dense deposit disease (DDD). In all 14 cases where electron microscopy was performed, the histologic diagnosis was confirmed. In nine cases the diagnosis of DDD was easily made in histologic sections on the basis of ribbon-like, brightly PAS positive thickening of the GBM, without "splitting" and with relatively slight mesangial proliferation. However, in five cases the picture closely resembled MPGN Type I, with hypercellularity, "splitting" and only focal ribbon-like thickening of the GBM, which required oil immersion for recognition. There was no correlation between the serum C3 levels and the morphologic diagnosis: nine (4 MPGN Type I, 5DDD) had persistently low C3 levels, two (1 MPGN Tye I, 1DDD) were normocomplementemic, and in 16, the C3 levels varied. C3 levels increased with time in nearly all patients. The clinical course was similar in patients with MPGN Type I and DDD. Significant correlations between the rate of development of renal failure and sex, age of onset, nephrotic syndrome or therapy could not be made. The five year survival rate was 87%; 12 developed renal insufficiency by five years. Although morphologically distinct, these findings suggest that DDD is clinically indistinguishable from MPGN Type I.
Insights
Dense deposit disease (DDD) and membranoproliferative glomerulonephritis (MPGN) Type I are morphologically distinct but clinically similar kidney diseases. Histologic review confirmed diagnoses, with DDD showing ribbon-like GBM thickening, while MPGN Type I presented with hypercellularity.
Area of Science:
- Nephrology
- Pathology
- Immunology
Background:
- Membranoproliferative glomerulonephritis (MPGN) encompasses several kidney diseases.
- Dense deposit disease (DDD) is a rare form of MPGN characterized by electron-dense deposits in the glomerular basement membrane.
- Distinguishing between MPGN Type I and DDD can be challenging based on light microscopy alone.
Purpose of the Study:
- To review and classify histologic findings in patients initially diagnosed with MPGN.
- To compare the histologic features and clinical courses of MPGN Type I and DDD.
- To assess the utility of electron microscopy in differentiating these conditions.
Main Methods:
- Histologic review of 27 kidney biopsy samples.
- Classification into MPGN Type I and DDD based on light microscopy.
- Confirmation of diagnoses using electron microscopy where available.
- Analysis of serum C3 complement levels and clinical data.
Main Results:
- 13 patients were diagnosed with MPGN Type I and 14 with DDD.
- Electron microscopy confirmed diagnoses in all cases where performed.
- DDD often showed ribbon-like GBM thickening, while MPGN Type I had hypercellularity and GBM splitting.
- Serum C3 levels showed no correlation with morphologic diagnosis and tended to normalize over time.
- Clinical courses and renal failure progression were similar between MPGN Type I and DDD.
- Five-year survival was 87%, with 12 patients developing renal insufficiency.
Conclusions:
- Dense deposit disease (DDD) and MPGN Type I are morphologically distinct entities.
- Despite histologic differences, DDD and MPGN Type I exhibit similar clinical presentations and outcomes.
- Electron microscopy is crucial for accurate differentiation of DDD and MPGN Type I.
- Serum C3 levels are not reliable predictors for distinguishing between DDD and MPGN Type I.