How to spot zebras – Behçet’s disease

Behçet’s disease is an autoinflammatory, multisystem disease that can potentially affect any part of the body from the brain down to the big toe. Although described since the time of Hippocrates, it was more recently characterised by the Turkish dermatologist Halushi Behçet in the mid-20th century.¹

Prevalence

Behçet’s is prevalent in regions such as Turkey, the Middle East and Japan, where it is more common than asthma and a major cause of blindness. In the UK, the disease is much rarer. The best estimate is that there are only 800 patients with this diagnosis in England. The true figure is, however, probably significantly higher, as the diagnosis is so rarely considered in a person native to the UK.

Behçet’s can also affect children. Although the incidence and prevalence in this group are not yet known, the condition is encountered even less in children than adults. A major surveillance study of Behçet’s among children and young people in the UK is currently under way, which should provide some answers.²

Presentation

When considering Behçet’s syndrome, it is crucial to take a good history, looking at the whole patient and not just the area of new symptoms. Behçet’s typically presents with severe recurrent aphthous ulceration of the mouth, often with genital ulcers, which are negative for virus. There may also be inflammation of the eye (uveitis) and skin rashes (typically a papular pustular acne-like eruption, or erythema nodosum). Rarely, it can present as deep vein thromboses, inflammatory bowel disease or even with neurological features.

Often most or all of these occur together. Sometimes, however, the development is staggered and only emerges with a good, detailed history. Either way, the development of severe genital ulcers in the absence of infection and a background of frequent mouth ulcers, inflammatory eye disease or skin rashes should provide the stripes for a GP to identify this zebra.

Differential diagnosis

The key differentials for Behçet’s that must be excluded before the diagnosis can be made include Crohn’s disease (skin, mucosal and bowel features), coeliac disease (skin and mucosal lesions) and lupus (mucosal and cutaneous disease).

Other rarer blistering skin lesions such as bullous pemphigoid/pemphigus and Sweet’s disease can also be confused with Behçet’s and require specialist confirmation. In children, the major differential diagnosis is Crohn’s.

Investigation

Behçet’s should especially be considered in people with severe genital ulceration, yet negative tests for viruses or other infections.

Ensure that any genital lesions are appropriately swabbed, ideally in a genitourinary medicine clinic unless the appropriate facilities are available in house.

Genital ulcers in children can be a major worry, as in addition to investigating for virus, child protection measures may need to be considered.

Apart from tests to exclude local infection, simple blood tests to measure inflammation (ESR, CRP), autoantibodies (ANA) and a general FBC and biochemical profile are helpful to exclude other conditions. In the case of bowel disease, appropriate gastroenterological investigations, including calprotectin, colonoscopy and gastroenterology referral are mandatory.

Diagnosis

Data from a UK patient group survey in 2011 revealed a typical time lag of around 12 years from the start of symptoms to diagnosis.

During this time most patients had attended up to six different specialists and a number of hospitals, all for different aspects of the same problem. Perhaps that stemmed from our incorrect assumption that this is a

rare exotic curiosity and not something that we can encounter in normal practice.

The key to diagnosing Behçet’s is to actually think of it. This seems to be especially difficult in a white British patient who has never set foot out of their home town – let alone come from a Silk Road country. But this disease is found in such people, in contrast to what we might have read in textbooks from the past.

Management

Once the diagnosis of Behçet’s is considered, the clinical picture often just fits into place. It’s then important to seek specialist help. Treatment for Behçet’s ranges from simple mouthwash and steroid creams through to immunosuppressants, and the high-cost biologic drugs.

Eye disease in Behçet’s is a medical emergency as it can cause blindness, as is vascular disease as you need to prevent embolism, stroke, and even rupture of potential pulmonary aneurysm.³

Most specialists should be able to investigate their particular organ, but rheumatologists perhaps have the most relevant experience and so are most appropriate for managing complex multisystem disease.

Professor Robert Moots is a professor of rheumatology at the University of Liverpool and the director of the National Centre of Excellence for Behçet’s Syndrome in Liverpool