306 Renal vascular lesions in childhood-onset lupus nephritis: a tertiary centre experience

BackgroundThe clinical significance of renal vascular lesions remains unknown in childhood-onset lupus nephritis (LN) and is not currently factored into WHO and ISN/RPS classification.ObjectivesThe aim of this study is to determine the incidence and outcomes of childhood-onset LN in the presence of these lesions.MethodsWe conducted a retrospective review at the tertiary paediatric nephrology centre in Hong Kong of children with LN who presented before 18 years with active follow-ups for 12 or more months by July 2020. Estimated glomerular filtration rate (eGFR) was calculated by modified Schwartz and CKD-EPI formula as appropriate.ResultsAmong 90 children with childhood-onset systemic lupus erythematosus, 61 patients (68%; mean age of 13.2 ±3.4 years; 85% girls) diagnosed to have biopsy-proven LN. The predominant presentation was nephritic-nephrotic syndrome (n=30, 50%), with 4 patients required acute dialysis. One (4%), 17 (28%), 29 (48%), 9 (15%), 4 (7%) and 1 (2%) patients had class II (lupus podocytopathy), III, IV, III/IV + V, V and VI LN, respectively.Of the 61 patients with LN, renal vascular lesions were observed in 9 children (15%) at a mean age of 14.1 ±4.3 years, including lupus vasculopathy (LV; n=4, 7%), thrombotic microangiopathy (TMA; n=4, 7%) and true vasculitis (n=1, 2%). Eight patients had co-existing proliferative LN (Class III [n=3]; IV [n=3]; mixed III/IV and V [n=2]) and one patient had pure membranous LN. All children except two developed nephritic-nephrotic syndrome and AKI, and acute dialysis were initiated in 2 patients with TMA. At presentation, patients with renal vascular lesions had a significantly lower median eGFR (21.0, IQR 14.0–51.0 versus 88, IQR 48.5–107.5 ml/1.73 m2/min; p=0.011) but similar degree of proteinuria (3.1, IQR 2.4–8.04 versus 2.5, IQR 1.3–5.1 mg/mg) than those without such lesions.Treatments were heterogeneous due to variable disease severity. In addition to pulse methylprednisolone, 6 and 3 patients received induction therapies with intravenous cyclophosphamide and mycophenolate mofetil, respectively. Three patients with severe AKI (LV n=2; TMA n=1; mean GFR 18.6 ml/1.73 m2/min) responded to rituximab as add-on rescue therapies and eventually did not require acute dialysis. Therapeutic plasma exchange was performed in three patients with TMA as adjunctive therapies. Following induction, 6 patients attained complete remission and had normal GFR and no proteinuria at last follow-up. Three patients failed to