Renal involvement in hypocomplementaemic urticarial vasculitis syndrome: a report of three paediatric cases.

Objective: To describe the diagnosis and management of renal disease in three paediatric cases of hypocomplementaemic urticarial vasculitis syndrome (HUVS).

Methods: Three children who were diagnosed with HUVS and developed abnormalities of renal function during the disease course are described.

Results: Urinary findings were heterogeneous: all the patients developed persistent microhaematuria, which was isolated in patient 1, associated with mild proteinuria in patient 2 and with nephrotic syndrome in patient 3. Renal biopsies were performed in all the patients: patients 1 and 2, who had normal levels of serum autoantibodies, shared a full-house IF (C3, C1q and Ig deposits), compatible with an SLE-like disease; patient 3 showed negative staining for IgG and IgM, but developed positive anti-dsDNA without fulfilling criteria for the diagnosis of SLE.

Conclusion: Renal involvement in HUVS is probably more frequent and more severe than in adults and may appear later. Isolated microhaematuria can be the only sign of subclinical renal involvement: its role should not be underestimated and a renal biopsy should be considered. Previous observations of rapidly progressive nephritis and consequent end-stage renal disease in children suggest the need for prompt diagnosis and treatment of renal involvement.