Allergic vasculitis. A histological and immunofluorescent study of lesional and non-lesional skin in relation to circulating immune complexes.

This study concerns 57 patients who fulfilled histological criteria for the diagnosis allergic vasculitis. For 37 of these patients, biopsy specimen were available from lesional and adjacent non-lesional skin. Histological signs of vasculitis were found at both sites, but in clinically normal skin the perivascular infiltrate was less dense and neutrophils and eosinophils were sparse or absent. Fibrin was found in only ten patients and occurred less frequently in non-lesional skin. Deposits of immune complexes and/or complement were detected by immunofluorescence in 49 of the 57 patients. Hardly any differences between lesional and non-lesional skin were found with immunofluorescent microscopy. Circulating immune complexes were detected in 45 of the 56 available sera. A relationship was found between the class of immunoglobulin in immune complexes in the vessel wall and in the circulation. Moreover, the class of immunoglobulin seemed to be related to the course, the extracutaneous involvement, and the presence of associated diseases. No explanation was found for the histological differences observed between lesional and non-lesional skin.