The clinical significance of a pathergy reaction in patients with Behcet's disease.

This study was done to evaluate the frequency, intensity, and specificity of a positive pathergy reaction (PR) in Behcet's disease (BD) patients, to clarify an association between the PR and the clinical features or disease severity, and to assess whether patients with pustule formation at the venous puncture site (PFVPS) without positive PR could be regarded as a positive reaction. The PR was tested in 64 BD patients, 74 disease controls, and 20 healthy controls. Venous PR was performed in 8 BD patients with PFVPS. Follow-up PR was done in 14 patients with positive reaction during inactive phase. The PR was positive in 35.9% of BD patients, in 1 patient among disease controls, and in none of healthy controls. The pustule formation was observed in one BD patient. There was no statistical significance between positive PR and the clinical variables. The mean clinical activity score of BD patients with positive PR was similar to patients with negative reaction. Venous PR was positive in 7 patients. The follow-up PR was positive in 2 patients during inactive phase. Conclusively the positive PR appeared to be specific for BD, and was not associated with the clinical variables or disease severity, but was usually found during active phase in cases with positive reaction. The PFVPS in patients with negative PR might be considered to be positive.