Background: Hypocomplementemic urticarial vasculitis, described by MacDuffie in 1973, is rare. Some doubt surrounds its classification. We report a case of hypocomplementemic urticarial vasculitis (MacDuffie syndrome) treated with dapsone with a favorable outcome.

Methods: Over a number of years, a 43-year-old man presented urticarial vasculitis attacks with palpebral oedema and systemic symptoms such as fever and arthralgia. In 2006, MacDuffie syndrome was diagnosed on the grounds of positive anti-C1q antibodies. Treatment with dapsone was started and resulted in considerable improvement.

Conclusions: Hypocomplementemic urticarial vasculitis is characterized by urticarial vasculitis lesions, leucocytoclastic vasculitis and systemic symptoms. The latter symptoms are similar to those of systemic lupus erythematosus (SLE), and some authors have suggested that MacDuffie syndrome may in fact belong to SLE. Diagnosis is based on clinical appearance, histology and the presence of anti-C1q antibodies. There is no specific treatment for hypocomplementemic urticarial vasculitis. Immunosuppressant therapy can be used for lesions refractory to systemic corticosteroids.