Giant cell arteritis

What is giant cell arteritis?

Giant cell arteritis is a form of vasculitis that most commonly affects the arteries of the scalp and head; as such, it is also known as temporal arteritis [1]. Giant cell arteritis can also cause anterior ischaemic optic neuropathy, cerebral arteritis, and the aortic arch syndrome.

It is characterised by a severe headache, visual symptoms, malaise, and fever [2].

Who gets giant cell arteritis?

The incidence of giant cell arteritis ranges from 5.8 to 31.3 per 100,000 of the population, and the prevalence is estimated at 30.4 cases per 100,000 [2].

Giant cell arteritis occurs only in adults over the age of 50 years and peaks between the ages of 70 and 80 years [1]. It is more frequent in women than in men and most often affects Caucasians [1].

In 50% of cases, giant cell arteritis is associated with polymyalgia rheumatica (PMR), a rheumatic condition that causes widespread aching and stiffness. It is estimated that 5–15% of people with PMR may develop giant cell arteritis [1].

What causes giant cell arteritis?

Giant cell arteritis is a large vessel vasculitis of unknown cause [1]. The symptoms of giant cell arteritis are due to occlusion of the affected arteries.

Age, genetics, and infection may be implicated in its causation [3]. The human leukocyte antigen (HLA) DR4 serotype has been correlated with giant cell arteritis and PMR [3].

What are the clinical features of giant cell arteritis?

The clinical features of giant cell arteritis are typically [1]:

• A new, persisting headache
• A tender scalp and temples
• Jaw claudication
• Abrupt onset of visual changes, including blurring, double vision, and blindness
• Flu-like symptoms such as fatigue, fever, and loss of appetite
• Diminished or absent temporal, occipital, or facial artery pulses.

The cutaneous manifestations of giant cell arteritis

Cutaneous manifestations of giant cell arteritis are rare and may occur months after the onset of other symptoms; these manifestations include [2,4]:

• Erythema, purpura, induration, and bullae
• Tender nodules, ulcers or necrosis
• Periorbital ecchymosis
• Glossitis
• Facial oedema
• Hair loss.

Late cutaneous manifestations include ulceration and necrosis of the frontotemporal scalp and tongue [4].

Giant cell arteritis may rarely affect another site, such as the lower limb, but widespread skin lesions are rare. This type of lesion are caused by occlusion of small vessels in the dermis or subcutis [2].

What are the complications of giant cell arteritis?

It is estimated that 13–19% of patients with giant cell arteritis experience ischaemia of an optic artery, causing sudden partial or complete vision loss that may be permanent [1,2].

Patients who develop scalp necrosis have an increased risk of vision loss and mortality [2].

Other complications can include gangrene of the tongue or nasal septum [5].

How is giant cell arteritis diagnosed?

The diagnosis of giant cell arteritis is based on the clinical features and the results of investigations.

• The inflammatory markers, erythrocyte sedimentation rate (ESR) and C-reactive protein, are raised.
• Biopsy reveals granulomatous inflammation of large blood vessels — most commonly, the branches of the external carotid and vertebral arteries [2].
• The histology of a cutaneous lesion is non-specific and a negative biopsy does not exclude the diagnosis.
• Blood cultures may be necessary to exclude a systemic infection.
• Imaging of the temporal artery and other large blood vessels may helpful [6].

The American College of Rheumatology has suggested five criteria for the diagnosis of giant cell arteritis; these criteria are [5]:

• Age greater or equal to 50 years old
• New onset of a localised headache
• Tenderness of the temporal artery
• Elevated ESR (> 50 mm/hour)
• Inflammatory infiltrates and multinucleated giant cells on biopsy.

The presence of three or more criteria has a 93.5% sensitivity and a 91.2% specificity for the diagnosis [5].

What is the differential diagnosis for giant cell arteritis?

The differential diagnosis for giant cell arteritis may include [3]:

• Other forms of vasculitis with constitutional symptoms and elevated inflammatory markers
• Takayasu arteritis, which has indistinguishable histopathological findings but occurs at a younger age, typically before the age of 40 years
• Non-arteritic anterior ischaemic optic neuropathy, presents with sudden monocular vision loss but lacks other features of giant cell arteritis.
• Systemic infection, causing fever, myalgia, arthralgia, headache, and elevated inflammatory markers.

What is the treatment for giant cell arteritis?

If there is a strong clinical suspicion of giant cell arteritis, systemic steroid treatment should be initiated immediately to decrease the risk of a loss of vision [6].

Typically, 40–60 mg of oral prednisone daily is prescribed for a minimum of 4 weeks, which may be preceded by intravenous methylprednisolone sodium succinate if there is visual impairment. The steroid dose is tapered down over 1–2 years [5]. Bone protection, such as calcium and vitamin D supplementation or bisphosphonate medication, may be necessary for some patients due to the side effects of long-term corticosteroid use [1].

In some cases, adjunctive immunomodulatory medication may be used, such as methotrexate or tocilizumab [6].

Low–dose aspirin is prescribed concurrently to prevent ischaemic events [6].

Occasionally, a skin graft is required to repair persistent ulceration [2].

What is the outcome for giant cell arteritis?

Giant cell arteritis is usually self-limiting and resolves over months to years [3]. Relapses can occur as the corticosteroid dose is reduced and require the dose to be increased temporarily [6].

New-onset visual loss is rare once corticosteroid treatment is started [3].

Giant cell arteritis is associated with increased cardiovascular morbidity and mortality [2].