Dapsone is an effective therapy for the skin lesions of subacute cutaneous lupus erythematosus and urticarial vasculitis in a patient with C2 deficiency.

The deficiency of second component of complement (C2d) is the most common hereditary complement deficiency. Patients with C2 deficiency are frequently associated with an auto-immune disease process, in particular, systemic lupus erythematosus (LE)-like syndrome and/or vasculitic syndrome or bacterial infections. C2d has been associated with the LE subset of subacute cutaneous LE (SCLE), the presence of anti-Ro (SSA) antibodies, and the human leukocyte antigen (HLA) types A10, B18, DR2. We describe the clinical, serologic and immunogenetic data in a patient with manifestations of Sjögren's syndrome who developed urticarial vasculitis and photosensitive annular SCLE which were effectively treated with oral dapsone. Our case illustrates the dynamic nature of LE.