Behcet disease – causes, symptoms, diagnosis, treatment, pathology

Behcet disease – causes, symptoms, diagnosis, treatment, pathology


Behcet disease, is a rare disorder and most
of the symptoms are thought to be a result of an autoimmune process involving the blood
vessels – it’s a type of vasculitis. Among the family of disorders that cause vasculitis,
Behcet’s is fairly unique because it causes inflammation in blood vessels of all sizes
– small, medium, and larges ones – on both the arterial and venous side of the circulation. The underlying cause of Behcet’s is unknown,
but there are a number of clues. The biggest clue is that the human leukocyte
antigen, or HLA, genes seem to play a role, and this is based on the fact that having
a specific type–the HLA-B51 type–predisposes individuals to having Behcet disease. HLA genes encode proteins found on the surface
of immune cells, and play a key role in regulation of those cells, and since the disease is a
result of an autoimmune process, it makes sense that the HLA-B51 proteins could be involved. Another, clue is that an individual’s response
to viral and bacterial infections may be involved. For example, some individuals with Behcet’s
generate relatively high levels of antibodies to Helicobacter pylori which may go on to
damage blood vessel walls. This is an example of molecular mimicry where
an antibody to a foreign pathogen starts to cross-react and damage the person’s own
tissue. Individuals with Behcet’s also seem to have
a weakened innate immune system, a higher proportion of autoreactive T cells and activated
neutrophils which destroy healthy tissue, and altered levels of T helper cells and cytokines. In sum, the clues span genetic and environmental
factors and both the innate and adaptive immune system. When looking at the blood vessels in particular
– the classic finding is seeing lymphocytes in the walls of capillaries, veins, and arteries
of all sizes making them inflamed and boggy; sometimes the inflammation can get so severe
that the tissue around the vessel begins to die off completely. These changes make the endothelial lining
more likely to develop blood clots or aneurysms. Since the inflammation is happening in blood
vessels of all sizes throughout the body, individuals with Behcet’s can develop a
wide-range of symptoms. Having said that, most individuals initially
present with recurrent oral ulcers. Relative to aphthous ulcers, the oral ulcers
of Behcet disease can be larger, more painful, and take a few weeks to heal – sometimes recurring
before a previous round of ulcers has resolved, which means that they can be almost continuously
present. The genital ulcers that develop are similarly
painful and can develop around the anus, vulva, or scrotum. Eye inflammation can also develop, and can
present a number of different ways. One is anterior uveitis which causes a painful
decrease in vision, redness of the conjunctiva, and hypopyon which is also known as sterile
pus because inflammatory cells enter the anterior chamber of the eye even though there is no
infection present. Another is posterior uveitis which causes
a painless decrease in vision and visual field floaters. On rare occasions, there can also be other
types of eye inflammation including involvement of the optic nerve itself. Not surprising – any sort of eye inflammation
can potentially lead to vision loss and is therefore one of the most serious aspects
of the Behcet’s. Some individuals can also develop skin conditions
like folliculitis or erythema nodosum – an inflammation of the fat cells underneath the
skin. As Behcet disease develops, it can vary quite
a lot between individuals since it can affect every organ system. Some individuals may have joint stiffness
and abdominal pain while others develop meningitis and kidney disease The clinical diagnosis is often made based
on an individual having a pattern of symptoms consistent with the disease, in particular
recurrent oral and genital ulcers, as well as eye and skin lesions. There is no specific blood work that’s typically
done, but one interesting and unique test that can be used is the pathergy test. In a pathergy test, an individual is pricked
on the skin and then reassessed 1-2 days later. Normally, a small pin prick would heal, but
many patients with Behcet disease don’t heal normally, and instead develop a skin
lesion or ulcer at that spot. Treatment for Behcet disease is typically
geared at suppressing the immune system to help alleviate the symptoms. That includes the use of medications like
corticosteroids, biologic agents that block the effect of tumor necrosis factor, and even
intravenous immunoglobulin which can alter the immune system’s activity. Okay – let’s recap, Behcet’s is a rare
autoimmune disease that affects small, medium, and large arteries and veins, as well as capillaries. The underlying mechanism is unclear, but blood
vessels show a pattern of lymphocyte infiltration and surrounding tissue necrosis. Classical features include recurrent oral
and genital ulcers, uveitis, and skin lesions, but the disease can affect nearly every organ
system. Thanks for watching, you can help support
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