Skin hyperreactivity response (pathergy) in Behçet's disease.

Behçet's disease is very difficult to diagnose because its clinical signs overlap with those of other systemic diseases. Thus there is a clear need for nonclinical diagnostic criteria for Behçet's disease. The nonspecific cutaneous hyperreactivity response, pathergy, may serve as an important diagnostic indicator. A test for pathergy may also clarify the role of an immune complex mechanism in the pathogenesis of Behçet's disease. In our study of 11 patients with Behçet's disease, deposition of immunoglobulins or complement was not found 4 hours after histamine or saline injection. In contrast, 24 hours after histamine or saline injection, 10 of 11 patients responded positively both clinically and histologically during the active stage of their disease. Vasculitis was noted in only two patients. Thus in most patients no evidence of an immune complex mechanism was observed. We conclude that any nonspecific intracutaneous injection is a good clinical tool for the diagnosis of Behçet's disease.