Diagnosing Behcet's Disease
Diagnosis of Behcet's disease involves an evaluation of symptoms, a physical examination, and diagnostic tests. Tests that may be performed to help rule out other conditions (e.g., reactive arthritis, Crohn's disease) include biopsy of a lesion (oral, genital, or skin), lumbar puncture, and imaging tests (e.g., MRI scan). In many cases, the diagnosis is not confirmed for a number of months or even years.
Diagnostic criteria for Behcet's disease include development of mouth sores at least 3 times in a 12-month period and at least two of the following:
- Genital sores
- Uveitis or other eye inflammation (e.g., retinal vasculitis)
- Skin sores
- Positive pathergy test, also called a Behcetin reaction skin test
A pathergy test involves pricking the skin of the forearm with a sterile needle (to a depth of approximately 1/2 centimeter). The test is positive and suggestive of Behcet's disease if a red bump (nodule or pustule) larger than 2 millimeters develops at the site of the skin prick after 24 to 48 hours.