Medicine
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We identify and describe clinical findings in hypocomplementemic urticarial vasculitis syndrome (HUVS), an uncommon to rare illness related to systemic lupus erythematosus (SLE). A patient with recurrent, idiopathic urticaria-like lesions was diagnosed as having HUVS if a lesional biopsy showed leukocytoclastic vasculitis, the serum C1q was markedly decreased, and antibody to C1q was detected in the patient's serum. The clinical characteristics, serologic findings, and outcome of patients who met these criteria were determined from prospective and retrospective data, including hospital and office records, patient interviews, previously banked serum samples, and freshly drawn sera. ⋯ The pathogenesis of HUVS may involve humoral autoimmunity, although it is not clear how autoimmunity would participate in development of obstructive lung disease. Cigarette smoking appears to be a risk factor for fatal lung disease in HUVS. All patients with HUVS should be made aware of this possibility and should be advised, encouraged, and helped to avoid tobacco smoke.