Childhood Henoch-Schönlein purpura nephritis and IgA nephropathy: one disease entity?--A clinico-pathologically comparative study.

In order to characterize their relationship through clinicopathological comparison between IgA nephropathy and Henoch-Schönlein purpura nephritis (HSPN), 31 children with IgA nephropathy aged between 3 to 15 years and 120 children with HSPN aged between 4 to 15 years were compared with each other in clinical manifestation, blood biochemistry, serum immunology and follow-up study. Renal pathological findings under light microscope, immunofluorescence and electronic microscope were analyzed and also compared between 31 children with IgA nephropathy and 32 biopsied children with HSPN. The results showed that the onset age was over 12 years in 25.8% children with IgA nephropathy, but only 10% in HSPN (P < 0.05). The clinical patterns of IgA nephropathy and HSPN were similar, but extra-renal manifestations were more often in HSPN, all of them had skin purpura, 59% had gastrointestinal symptoms and 47% suffered from arthralgia, compared with only abdominal pain 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 (all P < 0.01). Thin basement membrane nephropathy was only found in 6.5% children with IgA nephropathy, no in HSPN. The electronic dense deposits in HSPN were sparse, loose and wildly spread in glomerular mesangium, subendothelial area and even intra basement membrane, but it was dense, lumpy and mostly limited in mesangium and paramesangium in IgA nephropathy. Predominant IgA deposits were found in 81.2% of HSPN, and overwhelming IgG deposits in 12.5% of HSPN with relatively weak IgA deposits, moreover 6.3% of HSPN showed linear IgG deposits in glomerular capillary. Totally 71.9% of HSPN had IgG deposits in glomeruli and only 19.4% of IgA nephropathy showed glomerular IgG deposits (P < 0.01). No IgG deposit was observed in 81.6% of IgA nephropathy, among them most showed IgA and IgM and/or C3 deposits, moreover overwhelming IgG deposits and linear IgG deposits couldn't be found in IgA nephropathy. Mean 20 months follow-up showed complete remission in 72.5% of HSPN, but only 19.4% in IgA nephropathy after 34 months follow-up. Moreover, 64.5% of IgA nephropathy had consistent hematuria and proteinuria and 16.1% had active nephritides (P < 0.05). It was concluded that significant clinico-pathological difference was found between HSPN and IgA nephropathy, which didn't support the one disease entity hypothesis. HSPN and IgA nephropathy are probably two diseases with similar immune abnormalities.