[A clinico-pathological study comparing Henoch-Schonlein purpura nephritis with IgA nephropathy in children].

OBJECTIVE: Henoch-Schonlein purpura nephritis (HSPN) and IgA nephropathy are very similar in immunopathological changes, and therefore some nephrologists considered that they are substantially one disease entity caused by IgA immune abnormalities, and IgA nephropathy is, in fact, a kind of HSPN without rashes. The present study aimed to characterize their relationship through clinico-pathological comparison between IgA nephropathy and HSPN.

METHODS: Thirty-one children with IgA nephropathy aged from 3 to 15 years and 120 children with HSPN aged between 4 to 15 years were enrolled in this study. Their clinical manifestations, blood biochemical test, serum immunology and follow-up data were collected and analyzed. Renal pathological findings in light microscopy, immunofluorescence and electron microscopy were analyzed and also compared between 31 children with IgA nephropathy and 32 children with HSPN.

RESULTS: The age of onset was over 12 years in 25.8% children with IgA nephropathy, but only in 10% with HSPN, and the difference was significant (P < 0.05). The clinical patterns of IgA nephropathy and HSPN were similar, but extra-renal manifestations were seen more often in HSPN, all of them had skin purpura, 59% had gastrointestinal symptoms and 47% suffered from arthralgia. While the abdominal pain occurred only in 3.2% children with IgA nephropathy. The renal pathological investigation showed global sclerosis in 35.5% of IgA nephropathy and 3.1% of HSPN, mesangial sclerosis in 41.9% of IgA nephropathy and 6.3% of HSPN, but endothelial proliferation in 65.6% of HSPN and 29% of IgA nephropathy. The differences were extremely significant (P < 0.01). Thin basement membrane nephropathy were only found in 6.5% children with IgA nephropathy, but in none with HSPN. The electronic dense deposits in HSPN were sparse, loose and widely spread in glomerular mesangium, subendothelial area and even intra basement membrane. While the deposits were dense, lumpy and mostly limited in mesangium and paramesangium in IgA nephropathy. IgG was found in glomerular immune deposits in 71.9% of HSPN, but only 19.4% of IgA nephropathy. No IgG deposit was observed in 81.6% of IgA nephropathy, among them most showed IgA and IgM and/or C(3) deposit. Predominant IgG deposits were found in 12.5% of HSPN with relatively weak IgA deposit, moreover 6.3% of HSPN showed linear IgG deposits in glomerular capillary wall, which couldn't be found in IgA nephropathy. The follow-up data of average 20 months showed complete remission in 72.5% of HSPN and 19.4% in IgA nephropathy after 34 months follow-up. Moreover, 64.5% of IgA nephropathy had consistent hematuria and proteinuria, 16.1% had active nephritides, the difference was significant (P < 0.05).

CONCLUSION: Significant clinico-pathological differences were found between HSPN and IgA nephropathy, which does not support the one disease entity hypothesis. HSPN and IgA nephropathy are probably two diseases with similar immune abnormalities.