In 1994, the Chapel Hill Consensus Conference named and defined the 10 most common forms of vasculitis according to vessel size (Box 110.1). This system is based on the fact that different forms of vasculitis attack different vessels.^1,² These criteria were established to differentiate specific types of vasculitis, but they are often used as diagnostic criteria. The vasculitic syndromes feature a great deal of heterogeneity and overlap, which leads to difficulty with regard to categorization.³ In addition, many patients display incomplete manifestations, thereby adding to the confusion. Emergency physicians should keep in mind the fact that nature does not always follow the patterns and artificial boundaries drawn by classification systems.⁴

Box 110.1

Chapel Hill Consensus Conference Classification of Primary Vasculitides

Large Vessel

Giant cell (temporal) arteritis

Takayasu arteritis

Medium Vessel

Polyarteritis nodosa

Kawasaki disease

Small Vessel

Wegener granulomatosis

Churg-Strauss syndrome

Microscopic polyangiitis

Henoch-Schönlein purpura

Cryoglobulinemic vasculitis

Cutaneous leukocytoclastic vasculitis

From Kallenberg CG. Vasculitis: clinical approach, pathophysiology, and treatment. Wien Klin Wochenschr 2000;112:656–9.

Temporal (Giant Cell) Arteritis

Temporal, or cranial or giant cell, arteritis is a granulomatous large vessel vasculitis that affects the extracranial branches of the carotid artery, particularly the temporal artery. Females are affected two to four times more often than males, and the disorder usually occurs in patients older than 55 years. Its incidence is estimated to be 1 per 3000 individuals older than 50. Up to 59% of the time it is associated with polymyalgia rheumatica, which is characterized by pain and stiffness in the shoulders, neck, and pelvis, along with an elevated erythrocyte sedimentation rate (ESR).

Takayasu Arteritis

Takayasu arteritis (also referred to as aortic arch syndrome) is a granulomatous large vessel vasculitis that primarily affects the aorta, its branches, and the pulmonary and coronary arteries.¹ This rare disease predominantly affects women in the 20- to 30-year-old age group and is more common in Asian and South American women. Mortality ranges from 10% to 75%.

Polyarteritis Nodosa

Polyarteritis nodosa is a multisystem necrotizing vasculitis of small- and medium-sized muscular arteries. Visceral and renal artery involvement is characteristic.³ The mean age at onset is 50 years, although it can occur at any age. Men, women, and racial groups are all affected equally. This rare disease affects fewer than 10 per 1 million persons worldwide.

Kawasaki Disease

Kawasaki disease, also referred to as mucocutaneous lymph node syndrome, primarily affects children younger than 5 years. This acute systemic vasculitis is a febrile multisystem disease that is the leading cause of acquired heart disease in children in the United States.¹ The disease occurs worldwide but predominates in Japan, Asia, and the United States.

Wegener Granulomatosis

Wegener granulomatosis is a vasculitis of the upper and lower respiratory tract and kidneys. A systemic small vessel vasculitis is also involved. It may occur at any age but has a mean onset at 40 years of age. Wegener granulomatosis affects men and women equally and involves whites more commonly than blacks.

Churg-Strauss Syndrome

Churg-Strauss syndrome is a rare small vessel vasculitis manifested by fever, asthma, and hypereosinophilia.¹ This disease is also referred to as allergic angiitis and granulomatosis, particularly when it affects the lungs. It is estimated that about 3 million people are affected worldwide, with an equal incidence between sexes. It is seen at all ages with a mean onset at 44 years of age.

Henoch-Schönlein Purpura

Henoch-Schönlein purpura (anaphylactoid purpura) is a small vessel vasculitis that predominantly affects children and is characterized by palpable purpura, arthralgia, glomerulonephritis, and gastrointestinal symptoms.³ Though also seen in adults, 75% of cases occur in children younger than 8 years. It is more common than other vasculitides and affects males more frequently than females in a 2 : 1 ratio. It has a peak incidence in winter and spring and usually follows an upper respiratory tract infection.

Cutaneous Leukocytoclastic Vasculitis

This disorder, also called hypersensitivity vasculitis or predominantly cutaneous vasculitis, involves small vessels of the skin and is the most common vasculitic manifestation seen in clinical practice.¹ It has an incidence of 15 per million.⁴ In about 70% of cases, cutaneous vasculitis occurs along with an underlying process such as infection, malignancy, medication exposure, and connective tissue disease or as a secondary manifestation of a primary systemic vasculitis.

Behçet Syndrome

Behçet syndrome is a multisystem inflammatory disease that affects vessels of all size.¹ It is manifested as recurrent aphthous oral and genital ulcerations along with ocular involvement. Behçet syndrome is most prevalent at ages 20 to 35 years, with males suffering more severe disease.

Pathophysiology

Vasculitis, also known as the vasculitides or the vasculitis syndromes, is a clinicopathologic process that results in inflammation and damage to blood vessels.³ Cell infiltration with inflammatory modulators causes swelling and changes in function of the vessel walls. This compromises vessel patency and integrity and leads to tissue ischemia, necrosis, and bleeding. Because most forms of vasculitis are not restricted to a certain vessel type or organ, the syndromes are broad and heterogeneous. Vasculitis is a systemic multiorgan disease, so the findings may be dominated by a single or a few clinical organ manifestations.⁴

Vasculitis can be separated into two broad categories. It may develop de novo as a primary manifestation of vessel inflammation without a known cause. Alternatively, it may be a secondary manifestation of an underlying disease or exposure to a drug. Distinction between primary and secondary vasculitis is essential because their pathophysiologic, prognostic, and therapeutic aspects differ.

Management of patients with the secondary forms of vasculitis needs to be directed toward the underlying disease process. The primary vasculitides, once thought to be uncommon, have proved to be much less rare than previously estimated, and awareness of the incidence and prevalence of all forms of vasculitis has recently increased.⁵ This chapter focuses on the primary or de novo vasculitides.

The pathophysiology of the vasculitis syndromes remains poorly understood, with variation between disease states contributing to the difficulty. It is also not clear why vasculitis develops in certain patients in response to antigenic stimuli and not in others; however, in each disease state, immunologic mechanisms play an active role in mediating blood vessel inflammation.¹ Blood vessels can be damaged by three potential mechanisms (Box 110.2).⁶