Behcet's syndrome

Last edited 01/2023 and last reviewed 05/2023

Behcet's syndrome is a systemic venulitis.
The aetiology of Behcet's disease is not fully understood, however, a combination of genetic and environmental factors may play a role (1):

  • there is a strong HLA association with HLA-B51; this genetic marker is found in around 60% of BD patients (1)
  • Herpes simplex virus-1 (HSV-1) and Streptococcus have been postulated as possible environmental triggers of BD (2)

International Study Group for Behcet's disease (ISG) criteria for the diagnosis of Behcet disease (1,2).

Recurrent oral ulceration

Minor aphthous, major aphthous, or herpetiform ulcers observed by the physician or patient, which have recurred at least 3 times over a 12-month period

Plus any 2 of the following:

Recurrent genital ulceration

Aphthous ulceration or scarring observed by the physician or patient

Eye lesions

Anterior uveitis, posterior uveitis, or cells in the vitreous on slit lamp examination; or retinal vasculitis detected by an ophthalmologist

Skin lesions

Erythema nodosum observed by the physician or patient, pseudofolliculitis, or papulopustular lesions; or acneiform nodules observed by the physician in a postadolescent patient who is not receiving corticosteroids

Positive pathergy test

Test interpreted as positive by the physician at 24-48 h

The International Criteria for Behcet's disease (ICBD) was developed because of low sensitivity of ISG clinical diagnostic criteria (3).

The ICBD criteria are outlined below:

Sign/Symptom Points
Ocular lesions 2
Genital aphthosis 2
Oral aphthosis 2
Skin lesions 1
Neurological manifestations 1
Vascular manifestations 1
Positive pathergy test (a) 1

(a) Pathergy test is optional. Where a pathergy test is conducted, 1 extra point may be added for a positive result

A patient scoring >= 4 points is classified as having Behcet's disease (3)

A study derived from multinational data showed that the ICBD criteria exhibits much improved sensitivity over the ISG criteria while maintaining reasonable specificity (3)