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Dr. Maria Michailidou



General Considerations

Vasculitis refers to a heterogeneous group of disorders that is characterized by inflammatory destruction of blood vessels. Inflamed blood vessels are liable to occlude or rupture or develop a thrombus, and thereby lose the ability to deliver oxygen and other nutrients to tissues and organs. Depending on the size, distribution, and severity of the affected vessels, vasculitis can result in clinical syndromes that vary in severity from a minor, self-limited rash to a life-threatening multisystem disorder.

Because it often begins with nonspecific symptoms and signs and unfolds slowly over weeks or months, vasculitis is one of the great diagnostic challenges in all of medicine. Yet, physicians who know the general and specific clinical clues for vasculitis can often learn to suspect when vasculitis is present at the bedside. Establishing the diagnosis of vasculitis requires confirmation by laboratory tests, usually a biopsy of an involved artery but sometimes an angiogram or a serologic test.

Treating vasculitis has become as rewarding as establishing the diagnosis. In the absence of treatment, most patients with systemic vasculitis will suffer and die. With treatment, the vast majority of patients will improve, many will achieve remission, and a few will be cured.  


Because the causes of most forms of vasculitis are not known, the vasculitides are classified according to their clinicopathologic features. Although no schema has been accepted universally, one frequently used classification system separates the vasculitides based first on whether the process is primary (ie, of unknown cause) or secondary to some other condition (eg, a connective tissue disease or infection). The vasculitides can then be further separated by the size of vessels usually affected—large-sized, medium-sized, or small-sized arteries . Finer distinctions among forms of vasculitis affecting the same size vessel can be made by other clinicopathologic characteristics. For example, Takayasu arteritis and giant cell arteritis are grouped together because they both can affect the aorta and other large arteries. However, they are distinguished from each other by their clinical differences, such as the age of onset. Takayasu arteritis is chiefly a disease of young women, while giant cell arteritis almost never occurs before age 50. To take another example, both Wegener granulomatosis and Churg-Strauss syndrome affect small-sized vessels and are associated with antineutrophil cytoplasmic antibodies (ANCA). But only Churg-Strauss syndrome is associated with asthma and striking levels of eosinophilia.   


Although classification systems are useful in highlighting differences among the vasculitides, the arbitrary categories suggest neater lines of demarcation than nature always recognizes. Despite being classified as a form of primary, medium-vessel vasculitis group, polyarteritis nodosa results from chronic hepatitis B or C infection in about 20% of cases and can affect small vessels. Until the causes of all forms of vasculitis are known, exceptions in the classification schema will be common.  


The epidemiology of individual forms of vasculitis is covered in the relevant chapters. In general, the vasculitides are relatively uncommon but not rare in Western countries: about 1 out of 2000 adults has some form of vasculitis, and each year vasculitis develops in approximately 1 in 7000 adults. In the United States, the most common forms of primary systemic vasculitis are giant cell arteritis, Wegener granulomatosis, and microscopic polyangiitis  

Clinical Findings

Although the presenting manifestations of vasculitis are protean, they can be grouped into five categories of clinical clues . The first general clue is that most forms of systemic vasculitis begin with constitutional symptoms (such as malaise, fever, sweats, fatigue, decreased appetite, and weight loss). These nonspecific symptoms, in the absence of more specific signs, usually effectively camouflage the vasculitic nature of the patient's illness. A second clue is that most forms of vasculitis unfold subacutely over weeks or months. In contrast to many patients with acute infections, patients with vasculitis usually cannot pinpoint the hour or the day that their illness began. More typically, patients with vasculitis will struggle to define the month or the season in which their nonspecific symptoms accumulated sufficiently to become memorable. A corollary of the subacute course typical of vasculitis is that the initial diagnosis of vasculitis is rarely made (correctly) in the intensive care unit. Although pulmonary hemorrhage, bowel infarction, or other devastating complications of vasculitis frequently result in a patient being admitted to the intensive care unit, these catastrophic events usually develop late, weeks or months after other clinical clues have suggested or established the patient's diagnosis.

The tendency of most forms of vasculitis to produce striking signs of inflammation constitutes a third general clue. Manifestations of inflammation can include fever, arthritis, rash, pericarditis, anemia of chronic disease, or a markedly elevated erythrocyte sedimentation rate. Pain is a fourth common feature of the vasculitides and can originate from many different sources, such as arthritis; myalgia; or infarction of a digit, nerve, bowel, or testicle. The fifth general clinical clue is that vasculitis tends to cause multisystem disease. The skin, joints, nervous system, kidneys, lung, and gastrointestinal tract are especially favorite targets of many different forms of vasculitis. Although specific forms of vasculitis can defy generalization, most vasculitides start with constitutional symptoms that evolve over weeks and months to a painful disorder marked by signs of inflammation and multiorgan injury.

Symptoms and Signs

In general, the skin and the peripheral nervous system signs are especially useful because they often develop early in the course of the disease and because they can be detected at the bedside. The onset of small-vessel vasculitis (eg, hepatitis C–associated vasculitis) is often heralded by palpable purpura, usually on the lower extremities, whereas medium-vessel diseases (eg, polyarteritis nodosa) more commonly produce nodules, ulcers, or digital gangrene.

The most characteristic nervous system manifestation of vasculitis is mononeuritis multiplex, which is defined as a distinctive peripheral neuropathy in which named peripheral nerves are infarcted one at a time. The nerve infarctions result from vasculitis of the vessels of the vasa nervorum, causing ischemia of a nerve. Clinically, the two features that characterize this neuropathy are the asynchrony and asymmetry of the symptoms and findings. These features are best illustrated by comparing mononeuritis multiplex with other peripheral neuropathies. With most forms of nonspecific neuropathy the patient experiences numbness and tingling in a symmetric, stocking or glove distribution, which develop so slowly that the patient cannot accurately date the onset of the neuropathy. Examination of these patients usually fails to identify the involvement of large, named nerves. In sharp contrast, the onset of mononeuritis multiplex is strikingly memorable: the patient will often recall the day that his foot drop or wrist drop began. The patient will also often vividly recall how the neuropathy progressed asynchronously so that each month or so a new area of the body (usually an extremity) became involved. On examination, the damage from mononeuritis multiplex can be mapped to individual, named nerves (eg, the peroneal, tibial, ulnar, radial, or median nerves). Almost all will have sensory abnormalities and about half will have weakness as well. Although mononeuritis multiplex is often bilateral, the lesions are usually asymmetric: the right hand may demonstrate a median nerve infarct while the left hand has an ulnar nerve lesion.

Mononeuritis multiplex produces such a characteristic clinical picture that usually it can be diagnosed at the bedside. Occasionally, identifying mononeuritis multiplex becomes difficult late in the course when the infarctions of so many nerves can coalesce to produce an unusually symmetric pattern of deficits. In most cases, the early history of sequential peripheral nerve lesions supports the diagnosis of vasculitic neuropathy. In some cases, proof of mononeuritis multiplex will require electrodiagnostic studies.

Mononeuritis multiplex is one of the physical findings in medicine of great differential diagnostic value. In the absence of diabetes or multiple compression injuries, mononeuritis multiplex usually means the patient has some form of vasculitis. Polyarteritis nodosa, microscopic polyangiitis (MPA), Churg-Strauss syndrome, and Wegener granulomatosis are the forms of vasculitis most likely to cause mononeuritis multiplex.

Laboratory Findings

Laboratory abnormalities accompany virtually every form of vasculitis (Table 28–5). Some abnormalities, such as anemia and an elevated erythrocyte sedimentation rate, are very nonspecific and can be seen with many other diseases. Other findings, such as red blood cell casts in the urine (indicating vasculitis of the glomerulus) or antineutrophil cytoplasmic antibodies (associated with Wegener granulomatosis), have much greater specificity.

Imaging Tests

The role of imaging tests depends greatly on the form of vasculitis suspected. Plain radiographs infrequently provide important clues except in Wegener granulomatosis, where views of the sinuses and chest may yield findings (albeit usually not specific ones). Computed tomography scans of the chest are more sensitive in Wegener granulomatosis. Angiograms are especially helpful in supporting or establishing the diagnosis of Takayasu arteritis, polyarteritis nodosa, and primary central nervous system vasculitis.

Special Tests

Biopsy of involved tissues is the most common method for establishing definitively the diagnosis of vasculitis. Skin, peripheral nerves, airways, arteries, kidney, and gut are the most common sampled tissues. In general, biopsies of symptomatic areas have a yield of about 66%, whereas biopsy of sites with no symptoms or findings have low yield. Special stains are sometimes required to reveal the degree of damage to particular arterial layers (such as the internal elastic lamina) or the extent of immune complex deposition.


An important general principle in the treatment of vasculitis is to make sure that the intensity of treatment fits the severity of vasculitis. Although most forms of vasculitis require aggressive treatment to prevent morbidity and mortality, some do not. Minor vasculitis limited to the skin and caused by drug reactions requires no therapy other than stopping the offending drug. In contrast, rapid and intensive therapy is required to prevent blindness from developing in giant cell arteritis or renal failure from complicating Wegener granulomatosis.

Another important principle of treatment is to limit the toxicity of therapy. When long-term prednisone is required, for example, appropriate measures to prevent osteoporosis should be initiated. If immunosuppression will result (as occurs with high-dose prednisone or immunosuppressive drugs), then prophylaxis against Pneumocystis carinii pneumonia should be started. Other potential toxicities of therapies must be monitored closely.