Urticarial vasculitis: symptoms, causes, diagnosis and treatment

Ordinary hives (urticaria) are itchy, raised weals that come and go within hours. The British Association of Dermatologists (BAD) says individual weals typically disappear of their own accord within 24 hours without a trace. Vasculitis UK explains that when urticaria lasts longer, for days or weeks, the blood vessels under the skin can show evidence of vasculitis, and the term urticarial vasculitis is used.

The NHS describes vasculitis as the name for a group of conditions that cause inflammation of the blood vessels, in which the immune system attacks healthy blood vessels, causing them to become swollen and narrow. It can range from a minor problem affecting only the skin to a more serious illness affecting organs such as the heart or kidneys.

BAD describes urticarial vasculitis as affecting a very small percentage of people with an urticarial rash.

The Primary Care Dermatology Society (PCDS) says the lesions persist for more than 24 hours and can be painful or tender as opposed to itchy. They often show small purple-red bruise-like spots and post-inflammatory hyperpigmentation, are sometimes more angular than classical hives, and most commonly affect the trunk and upper limbs. Vasculitis UK says people may experience a burning or painful sensation and skin discolouration when the rash subsides.

PCDS says both types may be associated with systemic symptoms such as angioedema (swelling under the skin), abdominal or chest pain, fever and joint pain, and that these are more apparent in the hypocomplementaemic form. BAD says people may feel unwell with joint and stomach pains.

It varies. PCDS says the normocomplementaemic form is usually localised to the skin and runs a relatively benign course lasting about three years. Vasculitis UK says that with monitoring, after 1 to 2 years people often settle into a pattern of quiet periods and flares, which may be triggered by an intercurrent infection, and that treatment strategies for prompt flare management are worked out.

For skin-limited cutaneous vasculitis in general, BAD says the outlook is good with full recovery in the majority of cases, although the rash may recur at intervals and affected areas can look darker for months before fading.

BAD says the cause of urticarial vasculitis is rarely found. Vasculitis UK says it may be triggered by another disease process, infection, cancer or a drug, that it has particularly been associated with hepatitis virus infection, and that most cases have no identified cause. It can also be a skin feature of another form of systemic vasculitis.

Some cases are associated with changes in the blood complement system, with falls in the level of complement components C3, C4 or C1q, or the presence of anti-C1q antibodies. This is called hypocomplementaemic urticarial vasculitis. Vasculitis UK notes the same abnormalities can be seen in lupus, which is why doctors keep lupus in mind. If a medicine is suspected, BAD advises stopping it only after advice from a doctor.

Weals that last longer than 24 hours or leave bruising should prompt a clinician to think beyond ordinary hives. BAD says the diagnosis is confirmed by examining a skin biopsy from one of the weals under the microscope, and that extensive blood tests should be undertaken because a cause is rarely found. PCDS notes that biopsy results are not always helpful and vary from minimal signs of vasculitis to much more obvious vasculitic change.

PCDS says the most important blood tests are complement C3 and C4 levels, repeated if reduced, along with urine tests, kidney tests, a blood count and inflammatory markers to look for kidney involvement. Vasculitis UK adds that tests may include CRP and ESR, C1q and anti-C1q antibodies, ANA and ANCA, and that chronic virus infections, other infections, inflammatory diseases and cancer should be looked for and excluded.

BAD says antihistamines are not very helpful in urticarial vasculitis, but other medicines that help inflammation can be used. Vasculitis UK says there is no high-quality trial evidence to guide treatment. The skin features may simply be treated with antihistamines and NSAIDs such as ibuprofen. Hydroxychloroquine, dapsone and colchicine can be tried, especially for relapsing disease, and corticosteroids work well but relapse can occur on withdrawal and they are more toxic.

PCDS says first-line treatment for the normocomplementaemic type is non-sedating antihistamines, whereas the hypocomplementaemic type often represents part of a broader immune problem and such patients require referral to secondary care, where systemic steroids, dapsone, colchicine and hydroxychloroquine may be used. Vasculitis UK says systemic disease usually demands higher-dose steroids with an immune-suppressing medicine, and that steroids should be avoided as far as possible for skin-limited disease.

The NHS recommends asking for an urgent GP appointment or help from NHS 111 if hives do not improve after 2 days, the rash is spreading, or hives keep coming back. BAD lists symptoms that suggest involvement beyond the skin in cutaneous vasculitis, which are a reason to be assessed promptly: fever, nausea and vomiting, blood in the urine, joint and muscle aches, muscle weakness, tingling or numbness in the hands or feet, chest pain, breathlessness or cough, abdominal pain and blood in the faeces.

The NHS says to seek help if hives come with swelling under the skin, and to call 999 for swelling of the lips, tongue or throat or difficulty breathing.

A GP can make the first assessment and arrange blood and urine tests and referral to dermatology, where a skin biopsy is carried out. If other organs are involved, other specialists, such as a kidney specialist, may be involved. PCDS says the hypocomplementaemic form requires referral to secondary care.

A private dermatology consultation can speed up the first appointment or provide a second opinion, but a skin biopsy and the same blood tests are needed either way.