Behçet’s syndrome (or Behçet’s disease) is named after a Turkish professor of dermatology who described the main features of the condition in 1937.
It had previously been described as long ago as the 5th century BC by Hippocrates, by a Chinese physician in the 5th century AD, and by several European physicians in the late 19th and early 20th century. Firstly, there a debate about whether it should be called Behçet’s disease or Behçet’s syndrome. A syndrome is a collection of clinical features that may, or may not, be one condition and may be the presentation of several similar conditions. As there are differences in the incidence of Behçet’s syndrome, and of its various manifestations in different countries, and since we do not yet know the exact cause, some physicians prefer to keep an open mind and use the term syndrome. Calling it Behçet’s disease may suggest that we know that it is a single entity with a single cause in all cases. Secondly, there is a debate about how one should diagnose the condition.
Diagnosis in the individual patient depends on the clinical acumen and experience of the physician. Various schemes of diagnosis have been suggested over the years, none of which is perfect. There is no absolute diagnostic test for the condition. A test known as the pathergy test has been investigated over the years. It consists of pricking the skin of the forearm with a sterile needle and seeing if a red lump appears after 48 hours. This was thought to be specific for the condition but is not considered as such now since it is positive only in a minority of patients, the frequency of positive tests is falling over the years and some ‘normal’ patients may have a positive test.
Diagnosis, therefore, depends on a high index of suspicion (see below) and prompt referral of the patient to a physician who has considerable knowledge and experience of the condition. There are so-called International Classification Criteria, but these are for research purposes to ensure that studies of (for example) causation or treatment include patients who are comparable in different centres. These criteria are not intended to be used for diagnosis in an individual patient.
The condition is most frequent in Turkey, North Africa and the Middle East, and in South East Asia. While it is rare in Western Europe, it must not be overlooked. Although there are differences in various studies, it is generally found that women are more frequently affected in Europe, men are more frequently affected in the Middle East and South East Asia, and in all regions men have more severe manifestations.
The cause of the condition is not known. A major disturbance of the immune system has been demonstrated in laboratory tests, but this is not thought to be the underlying cause. Some authorities have suggested an infective cause, but this has never been convincingly confirmed. It is known that there is a strong genetic predisposition. Detection of some of the markers (like blood groups), or antigens, on the white cells in the blood, which are genetically transmitted, show a high incidence of one known as HLA-B51 compared with the general population. However, this is not the cause, as most people with this marker do not have Behçet’s syndrome and, conversely, some patients with Behçet’s syndrome do not possess the HLA-B51 antigen. Nevertheless, there is often a strong family history of the syndrome, or just a family history of mouth ulceration.
Studies of involved tissues in patients with Behçet’s syndrome show white blood cells in and around blood vessels (i.e. inflammation) – and particularly around large and small veins. Large arteries may also be involved, but this is relatively rare. While some authorities have labelled this as a vasculitis, which usually means inflammation leading to injury or destruction of blood vessels, it is probably more accurate to call this a vasculopathy, which means involvement of blood vessels of all sizes for whatever cause. This all implies that continuing research into the causation of the condition is essential.