Clinicopathologic correlation of C1q nephropathy in children.

BACKGROUND: Clinicopathologic correlation of C1q nephropathy is clarified poorly. The aim of our study is to clarify clinicopathologic correlation in childhood C1q nephropathy. METHODS: Thirty children aged 3 to 15 years who met criteria proposed by Jennette and Hipp were enrolled in this study. RESULTS: According to their presentation at onset, children were divided into 2 groups: the asymptomatic urinary abnormalities (asymptomatic) group (n = 18) and the nephrotic syndrome (NS) group (n = 12). Light microscopy showed minimal change disease (MCD) in 22 children (73%), mesangial proliferative glomerulonephritis in 6 children (20%), and focal segmental glomerulosclerosis (FSGS) in 2 children (7%). Four children in the asymptomatic group and all children in the NS group were administered prednisolone and/or cyclosporine. Normal urinalysis results were found in 8 children in the asymptomatic group and 3 children in the NS group during the follow-up period of 3 to 15 years. Eight children in the NS group were frequent relapsers at the latest follow-up. Two children with FSGS (1 child, asymptomatic group; 1 child, NS group) received dialysis 10 and 15 years after the diagnosis. There were no differences in histological findings and clinical outcomes between the 2 groups. Four children with MCD in the NS group underwent a second biopsy. C1q deposits disappeared in 2 children, and 1 of these 2 children showed FSGS. CONCLUSION: Childhood C1q nephropathy is found in a wide clinical spectrum. Some children showed disappearance of C1q deposits through the follow-up period. A large number of children with C1q nephropathy showed MCD. However, FSGS may develop in some children on repeated biopsy. Therefore, long-term follow-up is needed in children with C1q nephropathy.