Mesangial hypercellularity in children: presenting features and outcomes

Mesangial hypercellularity (MH), in the absence of sclerosis or immune deposition, was a common finding on renal biopsy in our center. We studied 66 children with predominant MH. Among all patients older than 2.7 years, blood pressure (BP) percentile and glomerular filtration rate (GFR) remained stable. Serum albumin (Alb) trended higher (3.0 ± 0.2 start vs. 3.4 ± 0.2 end g/dl, p = 0.06) and urine protein/creatinine lower (4.2 ± 0.9 start vs. 2.3 ± 0.9 end mg/mg, p = 0.18) at the end of the study period. The proportion with stage 1 CKD remained constant: 94% start vs. 92% end. At end, Alb was lower in patients referred for nephrotic syndrome (NS): 4.4 ± 0.3 hematuria vs. 4.2 ± 0.2 proteinuria vs. 2.8 ± 0.3 NS g/dl, p < 0.05 vs. both. Alb was lower (p = 0.03) and urine protein/creatinine trended higher in patients with diffuse foot-process fusion (FPF). Twenty-five percent of patients with focal FPF developed NS, all had relapses, and 63% were steroid sensitive (SS). All but one with diffuse FPF presented with NS; 86% had relapses (mean 1 year) and 63% were SS. GFR trended higher at the end in those with matrix thickening (mat) (119.6 ± 4.7 no mat vs. 129.1 ± 2.6 mat ml/min per 1.73 m², p = 0.1). Those without mat were less SS (59% no mat vs. 80% mat) and were more likely to require alkylating agents (Alk) for NS. Among those with positive immunofluorescence (IF), 82% had immunoglobulin M (IgM) alone; those with positive IF were more SS and needed Alk for NS. MH predicts a favorable prognosis. FPF predicts NS and multiple relapses.