Histopathologic Study of Pathergy Test in Behçet's Disease

The pathergy test (PT) is important in the diagnosis of Behçet's disease (BD). However, misinterpretation of the test might cause false-positive or false-negative results. Therefore, immunopathologic and histopathologic tests are recommended with PT.

The aim of this study is to determine histopathologic findings of positive pathergy reaction at BD.

This study was performed on 23 patients with BD. All patients were in active period of the disease. After 48 h from the injection, biopsy was performed on positive pathergy lesions.

Of the specimen from positive PT lesions of patients with BD, nine revealed mixed type inflammatory cell infiltration (39.1%), two revealed lobular panniculitis without vasculitis (8.7%), two revealed neutrophil rich infiltration (8.7%), and five revealed lymphocyte rich infiltration (21.7%) at the subcutaneous tissue. Mixed type inflammatory cell infiltration (43.4%), endothelial swelling and thickening (17.3%), erythrocyte extravasation (26.0%), perivascular cell infiltration (13.0%), lymphocytic vascular reaction (8.6%), lymphocytic vasculitis (13.0%), and leukocytoclastic vasculitis (21.7%) were detected in dermis by histopathologic examinations. There was no statistically significant difference between histopathologic findings and sex, family history, and systemic involvement except uveitis.

This is an exceptional study since it is the first study that determines subcutaneous tissue findings of positive pathergy reaction in Behçet patients. In our study, uveitis was found to be statistically significant in the patients who had vasculitis in dermis. It can be a clue for prediction of disease severity and course. Further, studies that include wide number of patients will better illuminate the correlation between subcutaneous tissue findings and disease severity and clinical course.