Indications and limitations of histopathological skin investigation of Henoch-Schönlein purpura in children.

UNLABELLED Henoch-Schönlein purpura, the most common primary vasculitis of the child, may cause, in some cases with atypical clinical picture, diagnostic difficulties with a significant prognosis impact, especially when occasionally "silent" renal symptoms coexist. The purpose of our study is, on one hand, to determine the histopathological investigation needs of Henoch-Schönlein purpura in children with atypical cutaneous manifestations or incomplete forms of illness and, on the other hand, to point out the correlation between the cutaneous histopathological aspects and other clinical and biological manifestations. RESULTS Optical microscopy revealed signs of leukocytoclastic vasculitis in 11 of the 22 cases with ulcerative necrotic purpura and atypical clinical picture. Immunohistochemical examination proved that these were associated with IgA deposits on the vascular wall, sometimes accompanied by C3, fibrin, IgM and CD3. The severity of the skin manifestations was directly correlated with the severity of digestive and/or renal symptoms. CONCLUSIONS Skin biopsy is indicated only in the atypical or incomplete forms of disease to support positive diagnosis by immunohistochemical evidence of the vascular IgA deposits. The severity and persistence of the ulceronecrotic purpuric rash seems to be directly related rather to the severity of the other clinical manifestations (digestive or renal) than to the generalized extensively purpuric appearance.