Systemic Vasculitis at a Glance
- Heterogenous group of rare inflammatory conditions in which blood vessel walls are primarily targeted by an inflammatory reaction.
- Etiology unknown; geographic, environmental, and genetic factors may be important.
- Incidence up to 42 cases per million per year.
- Diagnosis often established in patients with multiple but variable organ involvement; supported by laboratory or radiologic studies and histologic evidence of inflammatory reaction in blood vessels.
- Cutaneous involvement can occur in any of the primary systemic vasculitic syndromes.
- Cutaneous features are often not sufficient to provide complete diagnosis and staging.
- Classification of the vasculitides is based on several factors including known etiology or disease association (primary vs. secondary forms), predominant size of involved vessels (small, medium, or large arteries), and additional clinical and laboratory data.
- Primary vasculitis is a diagnosis of exclusion after causes of secondary vascular inflammation have been ruled out.
- Determinants of prognosis and treatment include the specific vasculitic syndrome, whether critical organs are involved, the severity of involvement, and the rate of disease progression.
- Treatment often requires glucocorticoids and the use of other immunosuppressive drugs.
The term “vasculitis” can be defined broadly to mean inflammation of blood vessels. However, from the perspective of the practicing clinician, “vasculitis” is most commonly used to describe a group of diseases in which inflammation of the blood vessels is the major, but not only, pathologic process. The vasculitides are a wide-ranging set of diseases that are mostly idiopathic, rare, and multisystemic. These diseases involve such a variety of clinical presentations and pathologies that all clinicians in every medical and surgical specialty will encounter such patients.
Vasculitis of the skin is a frequent manifestation in many forms of vasculitis, especially small- and medium-vessel arteritis where skin lesions may be the presenting symptom of a systemic illness.
This chapter will focus on skin disease in the systemic vasculitides. Isolated forms of skin vasculitis and some of the systemic vasculitides are covered in Chapter 163. In addition to outlining the skin manifestations of vasculitis in general and for specific types of vasculitis, this chapter will provide an approach to patients with skin disease in which vasculitis is a diagnostic consideration.
With the probable exception of drug/toxin-induced vasculitis, all forms of idiopathic vasculitis are considered rare, “orphan” diseases in the United States (prevalences of less than 200,000 people); similar designations exist in Europe and elsewhere.
Vasculitis occurs in people of both sexes, all ages, and all major racial/ethnic groups. However, some forms are more common in certain groups. For example, Takayasu arteritis is substantially more common in women than men, Kawasaki disease is almost exclusively a disease of young children, and giant cell arteritis is limited to older adults. Granulomatosis with polyangilis (GPA) mostly occurs in Caucasians and Behçet disease is markedly more common in countries in the Eastern Mediterranean as well as Japan and Korea. The demographic differences among the ...