Erythema Multiforme: Immune Complex Vasculitis of the Superficial Cutaneous Microvasculature

Abstract

The specificity and incidence of deposits of immunoglobulin and complement in the walls of vessels in the superficial cutaneous microvasculature were evaluated in a prospective study of consecutive skin biopsy specimens submitted for evaluation by direct immunofluorescence. Of 597 specimens, 32 showed granular deposits of C3, either alone or associated with immunoglobulin in the vessels of the papillary dermis. In most cases, the immunoglobulin was identified as IgM. Rheumatoid arthritis was identified as the diagnosis in 19% of patients who were biopsied, while syndromes of vasculitis, connective tissue diseases and erythema multiforme were the diagnoses in 28%, 28% and 16% of the biopsies respectively. The immunofluorescent findings and inciting cause of 17 erythema multiforme lesions are presented. All biopsies from early lesions showed deposits of C3 alone, or with IgM globulin, in the microvasculature of the papillary dermis. Herpesvirus hominis (HSV) was the predisposing cause in 8 patients, and 9 patients had erythema multiforme of uncertain etiology. HSV antibody was predominantly IgG in 6 subjects as it was in 5 controls with recurrent HSV who did not experience erythema multiforme. This study suggests that deposits of immunoglobulin and complement in the superficial cutaneous microvasculature can be found in a wide spectrum of vasculitis syndromes, and that erythema multiforme is mediated by the deposition of immune reactants in these vessels.