Hypocomplementemic urticarial vasculitis

Other Names: Anti-C1q vasculitis; Mac Duffie hypocomplementemic urticarial vasculitis; Mac Duffie syndrome; McDuffie hypocomplementemic urticarial vasculitis; McDuffie syndrome

Hypocomplementemic urticarial vasculitis (HUV) is a rare form of vasculitis characterized by inflammation of the small blood vessels and low levels of complement proteins in the blood. HUV causes recurrent episodes of hives (urticaria) and painful skin lesions that itch or burn. Individuals with HUV may also have systemic, multiorgan involvement, causing arthritic joint pain; pulmonary (lung) disease; ocular (eye) inflammation; kidney inflammation; or various other symptoms.

Some scientists refer to the condition as HUV syndrome (HUVS) when it is more severe and there is significant systemic involvement. Other scientists call the condition HUVS in the absence of systemic disease. In some cases, the terms are used as synonyms. There appears to be controversy regarding the nomenclature and classification of HUV and HUVS, and whether they are distinct conditions or represent a continuum of the same disease.

Cause

Both genetic and environmental factors are thought to play a role in causing HUV. It generally occurs sporadically, but familial cases have been reported. It is thought to develop due to an abnormal immune system response involving specific proteins that work together to fight organisms that cause infections. In some cases HUV may be associated with an underlying infection or systemic diseases such as systemic lupus, Sjögren's syndrome, monoclonal gammopathy, or blood disorders.

Symptoms

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Complement deficiency
• Pruritus(Itching)
• Skin rash
• Small vessel vasculitis

30%-79% of people have these symptoms

• Abdominal pain(Pain in stomach)
• Angioedema
• Arthritis(Joint inflammation)
• Autoimmunity(Autoimmune disease)
• Conjunctivitis(Pink eye)
• Cough(Coughing)
• Dyspnea(Trouble breathing)
• Episcleritis(Inflammation of the thin layer on top of the white part of eye)
• Glomerulopathy
• Hematuria(Blood in urine)
• Hemoptysis(Coughing up blood)
• Irregular hyperpigmentation
• Nausea and vomiting
• Proteinuria(High urine protein levels)
• Renal insufficiency(Renal failure)
• Uveitis

Diagnosis

A diagnosis of HUV requires the presence of the two major criteria, as well as at least two minor criteria. The major criteria are hives (urticaria) for at least 6 months, and low levels of complement system proteins in the blood. The minor criteria are:

• Inflammation in the small veins of the dermis (diagnosed by biopsy)
• Joint pain or arthritis
• Mild kidney inflammation (glomerulonephritis)
• Eye inflammation (in the uvea or episclera)
• Recurrent abdominal pain
• The presence of anti-C1q antibodies (although this test is not widely available)
• Additional laboratory studies may include tests for kidney function tests and immunological status. A chest x-ray should be done in individuals found to have low levels of complement system proteins and breathing problems.

Treatment

There is no cure for HUV. Treatment varies depending on each person's signs and symptoms. Some cases of HUV respond to therapies commonly used for the treatment of lupus, including low-dose prednisone, hydroxychloroquine, and dapsone.

Prognosis

The long-term outlook (prognosis) for people with HUV varies from person to person. The prognosis largely depends on severity of systemic involvement and is influenced primarily by the severity of lung (pulmonary), heart, and kidney (renal) disease. When present, pulmonary disease (COPD) is the major cause of death. Cigarette smoking itself appears to be a strong risk factor for developing lung disease with HUV. Acute swelling of the larynx (laryngeal edema) can also be life-threatening. Although HUV is uncommon in childhood, the prognosis is worse for those affected at younger ages because of more frequent, severe renal involvement.

The prognosis can also be influenced by other underlying disorders that HUV is associated with. When HUV is associated with systemic lupus, the overlap of the two disease processes may cause relatively fast progression and poor prognosis, given that either disease can end fatally. Therefore, all patients diagnosed with HUV should also be examined for lupus (and possibly vice versa).

Because the symptoms and severity of HUV vary, it is not possible to predict the life expectancy for affected individuals.

NIH genetic and rare disease info

• NIH info on Hypocomplementemic urticarial vasculitis

Hypocomplementemic urticarial vasculitis is a rare disease.

Hypocomplementemic urticarial vasculitis Resources
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