Hypocomplementemic urticarial vasculitis: a rare presentation of systemic lupus erythematosus.

BACKGROUND Urticarial vasculitis is a small-vessel vasculitis, presenting clinically as persistent urticarial skin lesions and microscopically as leucocytoclastic vasculitis. Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a distinct type of urticarial vasculitis with multiorgan involvement, whose etiology and link with other diseases are still unknown. Some authors have suggested that HUVS can be accompanied by systemic lupus erythematosus (SLE), and others believe that it is a rare subtype of SLE. Urticarial vasculitis is seen in 7-8% of SLE, while 50% of HUVS patients are diagnosed with SLE. OBSERVATIONS AND RESULTS We report a case of HUVS associated with SLE with fatal outcome unresponsive to the combination of systemic corticosteroids and azathioprine. CONCLUSIONS SLE and HUVS share both clinical and laboratory features and are probably not separate entities. It is mostly likely that HUVS and SLE fall into the same spectrum of autoimmune diseases. HUVS is probably a subset of SLE. As both diseases can fatally, it should be kept in mind that the overlap of SLE and HUVS may exhibit a relatively rapid progression and poor prognosis.