Vasculitis is characterized by inflammation and necrosis of blood vessels, which can ultimately result in end-organ damage.1-3 The presence of fibrinoid necrosis of the vessel wall and an inflammatory infiltrate are hallmark histologic findings. Although often idiopathic, vasculitis is a reaction pattern that may be triggered by, among other causes, an underlying infection, malignancy, medication, or connective tissue diseases (Figure 1; Table 1). The skin is commonly affected, leading to a variety of clinical presentations. Pathognomonic is palpable purpura; that is, extravasation of red blood cells outside of vessels, leading to a raised purple lesion. Depending on the depth and size of the underlying vessel affected, the spectrum of clinical lesions varies from a reticulated erythema (livedo reticularis) due to disease of the superficial cutaneous plexus, to widespread purpura (Figure 2), to necrosis, to ulceration (Figure 3) due to disease in larger, deeper vessels. Patients may also present with papules, nodules, and/or urticaria (hive-like lesions). This spectrum of clinical presentation, the involvement of different end organs (eg, kidney, lung, central nervous system, gastrointestinal tract), and the varying types of inflammatory cells involved make classification confusing.
One working classification divides vasculitis by the size of the vessels involved, although overlap is common.4,5 Others have categorized vasculitis histologically by the type of cellular infiltrate within and around the affected vessels.1 This, too, is imperfect, as lesion age may alter the type of inflammatory infiltrate present.2,3,6 A combined classification is presented in Table 2. For example, necrotizing vasculitis consists of neutrophilic infiltrates, whereas granulomatous vasculitis contains macrophages within the infiltrate.2-7 Lymphocytic vasculitis may have either typical or atypical lymphocytes present in the infiltrate.8
Circulating immune (antibody-antigen) complexes, which deposit in blood vessel walls, have been implicated in the pathophysiology of vasculitis. Once deposited, they activate complement and produce anaphylatoxins (C3a, C4a, C5a), which leads to mast cell degranulation. Mast cell degranulation releases vasoactive substances, including histamine, which sustain the reaction by depositing additional immune complexes. The anaphylatoxin C5a, in particular, acts as a chemotactic agent for neutrophils, eosinophils, and monocytes. Phagocytosis, by the recruited inflammatory cells, leads to the release of elastase, which causes tissue damage, extravasation of red blood cells, vascular occlusion, and tissue necrosis.
The aim in evaluating a patient with vasculitis is to confirm the diagnosis, determine which end organs may be involved in the process, and determine the etiology of the disease (Table 3). Tissue biopsies will confirm the presence of vasculitis. Biopsies of perilesional skin may detect the type of immunoglobulin involved in the process, if performed early on. Tissue culture may aid in determining if the vasculitis is due to an infectious process.
Once a diagnosis is confirmed histologically, evaluation of other organ systems is necessary to determine the extent of the disease. A complete blood count, renal and liver function tests, stool guaiac, radiograph of the chest, and urinalysis should accompany a history and physical examination. To determine the etiology of the vasculitis, a laboratory evaluation should include antinuclear antibody and antineutrophilic cytoplasmic antibody tests, a rheumatoid factor, antistreptolysin O test and DNase, a hepatitis profile, cryoglobulin level, and serum protein electrophoresis. A throat culture and purified protein derivative (tuberculin test) should be performed to help exclude various potential causes. Tests evaluating for circulating immune complexes (eg, Raji cell assay) and serum complement levels may be of benefit in some patients.
If identified, and if possible, the causative agent should be addressed. Treatment of the vasculitis is based on the extent of the disease2,5(Table 4).
Mild disease, limited to the skin, can be treated with supportive care (eg, leg elevation, appropriate dressings). Drugs with limited adverse effect profiles, such as colchicines, dapsone, antihistamines, and/or nonsteroidal anti-inflammatory agents, among others, may also be used.2,5 For example, a patient whose disease is localized and limited to the leg due to a medication he or she had ingested would likely require only leg elevation, compression stockings, and the use of colchicines (0.6 mg twice daily).
If skin disease is extensive or systemic involvement is present, more aggressive treatment may be needed. These treatments include the use of systemic steroids, other anti-inflammatory agents, or immunosuppressants, among other potential agents.2,5 For example, a patient with widespread skin involvement and elevated liver function tests would be treated with prednisone (1 mg/kg). If the disease flared during the steroid taper, a steroid-sparing agent such as mycophenolate mofetil would be added.
It is important for practitioners to remember that other conditions, such as embolic and thrombotic diseases, may mimic vasculitis. Therefore, definitive diagnosis should always precede treatment.
1. Arnold HL, Odom RB, James WD. Andrew's Diseases of the Skin. Philadelphia, PA:WB Saunders Co; 1990.
2. Lawley TJ, Kubota Y. Vasculitis. Derm Clinics 1990;8:681-7.
3. Gibson LE, Su WPD. Cutaneous vasculitis. Derm Clinics 1995;21:1097-113.
4. Ghersetich I, Jorizzo JL, Lotti T. Working classification of vasculitis. Int Angiol 1995;14:101-6.
5. Lotti T, Ghersetich I, Comacchi C, Jorizzo JL. Cutaneous small-vessel vasculitis. J Am Acad Dermatol 1998;39:667-87.
6. Gibson LE. Cutaneous vasculitis: approach to diagnosis and systemic associations. Mayo Clin Proc 1990;65:221-9.
7. Gibson LE. Granulomatous vasculitis and the skin. Derm Clinics 1990;8:335-45.
8. Carlson JA, Mihm MC, LeBoit PE. Cutaneous lymphocytic vasculitis: a definition, a review and a proposed classification. Sem Diag Path 1996;13:72-90.
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