Immunofluorescent investigations in cutaneous vasculitis. II. Histotopical demonstration of IgD and fibrin.

The histotopical distribution of IgD and fibrin was examined in skin lesions of 12 patients with cutaneous vasculitis, by means of the direct IF method. IgD was found in 9 cases mostly in a striking fixation to the PMN-leucocytic inflammation cells. Homogeneous depositions of IgD in cutaneous blood vessel walls were seen twice. In 3 cases with older, lympho-histiocytic infiltrations, IgD was lacking. Fibrin was constantly present in the blood vessel walls of fresh and older vasculitis lesions, and showed up in the regions of "fibrinoid necrosis" in form of distorted vascular rings. Although neither IgD nor fibrin appear in a disease-specific histotopical distribution, their simultaneous in vivo demonstration, connected with the result of vascular bound complement, is a good aid to substantiate the diagnosis of cutaneous vasculitis.