Hypocomplementaemic urticarial vasculitis syndrome: a mimicker of systemic lupus erythematosus

A middle aged female patient presented with generalised palpable purpura associated with intense pruritus along with subconjunctival haemorrhage and orbital inflammation. There was extensive dermographism. Other systemic examinations were within normal limits. Haematological profile was normal except raised D-dimer. Skin biopsy revealed the presence of leucocytoclastic vasculitis. Antinuclear antibody was positive in a titre of 1 : 160, but antidouble-stranded DNA was negative. Urine examination revealed haematuria and proteinuria. Complement C3, C4 and C1q levels were decreased with the presence of anti-C1q antibody. There was a diagnostic dilemma between systemic lupus erythematosus and hypocomplementaemic urticarial vasculitis syndrome. However, as the patient did not fulfil the American College of Rheumatology criteria for systemic lupus erythematosus, but fulfilled all the criteria for hypocomplementaemic urticarial vasculitis syndrome, the case was finally diagnosed as hypocomplementaemic urticarial vasculitis syndrome and treated accordingly with favourable outcome.