Henoch-Schönlein purpura: clinicopathologic correlation of cutaneous vascular IgA deposits and the relationship to leukocytoclastic vasculitis.

Significant cutaneous vascular IgA deposits are common in Henoch-Schönlein purpura but not in other vasculitides. The specificity for IgA vascular deposits for Henoch-Schönlein purpura is not well defined. To examine the specificity of IgA vascular deposits for this disease, we compared clinicopathologic features of 92 cases with IgA vascular deposits and a direct immunofluorescence impression of vasculitis with 90 similar cases without IgA deposits. Henoch-Schönlein purpura was diagnosed in 24% of cases with vascular IgA deposits on direct immunofluorescence examination. IgA deposits were frequent in erythema nodosum and venous stasis-related problems and in cryoglobulinemia, coagulopathic vasculopathies, and livedoid vasculitis. Of our cases, 78% exhibited vascular fluorescence with multiple conjugates. No histologic or immunofluorescence pattern alone was specific. The diagnostic specificity for Henoch-Schönlein purpura is improved if gastrointestinal involvement, upper respiratory infection, or age < 20 years is present. We propose diagnostic criteria for Henoch-Schönlein purpura incorporating clinical findings yielding sensitivity and specificity > 90%.