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Glomerulonephritis in children with mixed connective tissue disease
S Ito1, T Nakamura, R Kurosawa
1Department of Pediatrics, Yokohama City University Medical Center, Urafunecho 4-57, Minamiku, Yokohama, Kanagawa, 232-0024 Japan. hi5-si@urahp.yokohama-cu.ac.jp
Insights
Children with mixed connective tissue disease (MCTD) often have silent kidney disease. Early renal biopsy and monitoring hypocomplementemia are crucial for diagnosing nephritis in juvenile MCTD.
Area of Science:
- Pediatric Rheumatology
- Nephrology
- Immunology
Background:
- Mixed connective tissue disease (MCTD) shares features with systemic lupus erythematosus (SLE).
- Juvenile MCTD carries a higher risk of nephritis than adult MCTD.
- The necessity of renal biopsy and the role of hypocomplementemia in juvenile MCTD nephritis remain unclear.
Purpose of the Study:
- To investigate the histopathological features of nephritis in juvenile MCTD.
- To assess the diagnostic value of renal biopsy in children with MCTD.
- To analyze the implications of hypocomplementemia in MCTD-associated nephropathy.
Main Methods:
- Renal biopsy was performed on 11 children with MCTD.
- A review of 71 juvenile MCTD cases (including the 11 patients) was conducted to determine nephritis frequency.
- Hypocomplementemia and pathological findings were analyzed in 41 MCTD nephritis cases.
Main Results:
- Glomerulonephritis was found in 6 of 11 biopsied children, with four showing no urinalysis abnormalities.
- Approximately 28% of juvenile MCTD cases presented with latent nephritis.
- Membranous nephropathy (MN) and mesangial proliferative glomerulonephritis (MPG) were common; hypocomplementemia was linked to MN and mixed MPG/MN forms.
Conclusions:
- Renal biopsy is recommended for children with MCTD due to a high incidence of asymptomatic nephritis.
- Hypocomplementemia in MCTD patients indicates a significant likelihood of glomerulonephritis, including membranous lesions.
Aims:
Mixed connective tissue disease (MCTD) has overlapping clinical features with systemic lupus erythematosus (SLE). Renal biopsy is necessary for all children with SLE to evaluate the prognosis, because they are at a quite high risk of developing renal complications. Furthermore, lupus nephritis and hypocomplementemia usually precede the appearance of clinical manifestations. Immune complex-mediated nephritis is one of the major complications of MCTD. Juvenile MCTD is known to be associated with a higher risk of nephritis than adult MCTD. However, it is uncertain whether all children with MCTD should be subjected to a renal biopsy, and whether most of those with hypocomplementemia present nephropathy, as in patients with SLE. We examined the histopathological characteristics of juvenile MCTD nephritis, the importance of renal biopsy and the implications of hypocomplementemia in our patients and reported cases of MCTD.
Material And Methods:
We performed renal biopsy in 11 children with MCTD and found 6 patients with glomerulonephritis. In addition, we studied the frequency and the characteristics of glomerulonephritis in 71 cases of juvenile MCTD (our 11 patients and 60 reported cases). We also analyzed the relationship between hypocomplementemia and pathological features in 41 cases of MCTD nephritis (23 adults, 18 children).
Results:
6 of our 11 patients had glomerulonephritis, but of them four had no abnormality in urinalysis at the time of biopsy. In 5 patients renal biopsy showed normal findings. Review of 71 cases of juvenile MCTD showed that of them 28% presented latent asymptomatic nephritis at the time of biopsy. Membranous nephropathy (MN) and mesangial proliferative glomerulonephritis (MPG) were common in MCTD. Interestingly, hypocomplementemia was more frequently observed in patients with MN or mixed form of MN and MPG (MPG/MN) than simple MPG based on our review of 41 cases (p < 0.01).
Conclusion:
A more aggressive indication of renal biopsy should be considered in children with MCTD because of the high incidence of non-clinical nephritis. The hypocomplementemia observed in patients with MCTD suggests the high frequency of glomerulonephritis, including membranous lesions.
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