Renal manifestations in hypocomplementic urticarial vasculitis syndrome: Is it a distinct pathology?

Hypocomplementic urticarial vasculitis syndrome (HUVS) is an autoimmune disease characterized by recurrent urticaria, arthritis, and glomerulonephritis (GN). Anti-C1q antibody is the marker of HUVS together with low levels of classical pathway complements which are C2, C3, C4, and C1q. We report a case of a 6-year-old boy who presented with episodes of rashes, injected conjunctiva, abdominal pain, and arthritis, diagnosed as HUVS. He had low C3, low CH50, normal C4, and positive C1q antibody. His urinalysis showed intermittent microscopic hematuria only. One year later, his laboratories showed persistent low C3 and positive Anti-ds DNA. The urinalysis showed hematuria, pyuria, and nephrotic-range proteinuria. Urine protein to creatinine ratio was 101.8 h mg/mmol. Kidney biopsy showed mesangioproliferative GN consistent with the diagnosis of HUVS. The patient was treated initially with prednisolone then azathioprine was added to the regimen. He showed good response with the disappearance of hematuria and proteinuria. Nine months later, he had no skin rashes with normal urinalysis and normal anti-ds DNA antibody. We report a case with HUVS and GN with positive anti-dsDNA antibody that revealed good response to combination of immunosuppressive therapy.