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SPECIFIC TYPES OF SMALL - VESSEL VASCULITIS

‘Allergic' or ‘hypersensitivity' vasculitis

This is a somewhat historically confused term, as the original descriptions probably included individuals with a variety of disorders that would now be considered separately. It was separated from HSP, but as the latter was decreed to occur only in children, adult HSP was never diagnosed and would have been included as a hypersensitivity vasculitis. Some authors now use the term idiopathic vasculitis in place of hypersensitivity vasculitis, although ideally an idiopathic diagnosis should really be reached by exclusion of specific causes. Generally, no cause is identifiable in about 50% of patients with CSVV.

Drug-induced purpura and vasculitis

Most cases of drug-induced vasculitis are not clinically distinguishable from other causes of a small-vessel vasculitis, but are discussed separately, as drugs should always be considered in the differential diagnosis of a vasculitic rash. In most cases, the pattern is of a predominantly lower leg, small-vessel disease. Potential causative agents include the following.

Henoch–Schönlein purpura

Henoch–Schönlein purpura is the characteristic type of small-vessel leukocytoclastic vasculitis. Lesions are as described earlier. Early lesions often have an urticated component or an inflammatory retiform pattern (Figs 14.17 and 14.18).

    Different criteria for the diagnosis make literature assessment difficult (e.g. some authors still restrict the diagnosis to childhood). However, the most logical approach appears to be for the term HSP to apply to IgA vasculitis.

    There are several studies documenting preceding sore throat and upper respiratory tract infection (especially in children, most commonly streptococcal infections) and familial clustering. In adults, drug treatments are also implicated, commonly antibiotics such as penicillins.

    The classic clinical associations are with arthralgia, gastrointestinal involvement (which may present as pain, bleeding, or intussusception, especially in children), and nephritis (IgA nephropathy). A common feature of HSP is recurrent episodes after initial improvement, which may occur on several occasions. In most cases, the overall tendency is toward improvement, but follow-up with monitoring of blood pressure and urinalysis is required.

Urticarial vasculitis

Urticarial vasculitis (Fig. 14.23, see also Ch. 9) is characterized by urticarial lesions that persist for more than 24 h, by comparison with ordinary urticaria, in which the lesions are more transient. The lesions are often more angular or stellate in shape compared with the circles and arcs of ordinary urticaria, and there may be associated purpura or bruising, although this can also occur in ordinary urticaria (especially if scratched due to itch). Pain may be present rather than the itch of more typical urticaria. There may be associated livedo reticularis, vasculitis, episcleritis, arthritis, nephritis, and other internal organ involvement.

    Urticarial vasculitis may occur in association with various immune abnormalities, such as systemic lupus erythematosus (SLE), Sjögren syndrome, mixed cryoglobulinemia, IgA myeloma, and monoclonal IgM gammopathy (Schnitzler syndrome). Viral infections, such as infectious mononucleosis and hepatitis C, may cause urticarial vasculitis without associated cryoglobulinemia. The most important association is with low complement levels, as this group has a high frequency of SLE (about 50%) and multisystem disease. This is known as the hypocomplementemic urticarial vasculitis syndrome (HUVS). Most such patients are women,
and nearly all have immunoreactants at the basement membrane zone
on direct immunofluorescence (positive lupus band). By contrast, normocomplementemic urticarial vasculitis patients have a less prominent female predominance, only a few percent have SLE, and the prognosis is generally better.

    The most important differential diagnosis is from ‘ordinary' urticaria (Ch.9), and making the distinction between normocomplementemic urticarial vasculitis and HUVS.

    Treatments include antihistamines (usually relatively unhelpful, by contrast to in ordinary urticaria), corticosteroids, dapsone, colchicine, and hydroxychloroquine.

Figure 14.23 Urticarial vasculitis lesions on the nape of the neck and upper back. These may be more irregularly shaped than ordinary urticarial lesions, are more likely to have a purpuric component, and each lesion may often last a few days.

PRACTICE POINTS

Features that suggest urticarial rather than ordinary vasculitis include:

Waldenström hypergammaglobulinemic purpura

This disorder (Fig.14.24) is probably underdiagnosed. It is typically a transient eruption that affects the lower legs in young women, often provoked by exercise, heat, and prolonged sitting or standing. It may occur over many years.

    The lesions are petechial, occasionally palpable, and last for a few days, with some residual staining as they resolve. They are often asymptomatic but sometimes itch or burn when the eruption appears. Many patients are otherwise well, but some have arthritis, Sjögren syndrome, sarcoidosis, or other systemic diseases, and mild anemia is common.

    Platelet counts and tests of clotting are normal, but ESR is often elevated, and there is a polyclonal increase in gamma-globulins (usually IgG) and sometimes positive antinuclear antibody or rheumatoid factor tests. Deposition of IgM, IgG, or complement C3 may be demonstrated in skin biopsies.

    The differential diagnosis may include many causes of CSVV, or of simple purpura or capillaritis.

    Treatment is often not required other than avoiding likely triggers, and the risks and costs of plasmapheresis or immunosuppressive therapy often outweigh the advantages. Aspirin and other antiplatelet agents are helpful in some cases.

Figure 14.24 Waldenström hypergammaglobulinemic purpura. The lower leg in young women is a typical site of involvement. Lesions may be provoked by exercise.

Bacterial endocarditis

The clinical picture in subacute bacterial endocarditis (SBE) is primarily due to immune complex disease causing a small-vessel leukocytoclastic vasculitis (Figs 14.25 and 14.26). This is accompanied by splinter hemorrhages, retinal or conjunctival hemorrhages or edema, and lesions on the hands and fingers (Osler nodes, Fig. 14.27, and Janeway lesions). The presence of bacteria has been documented in the latter lesions, suggesting that at least some of the features of SBE are due to infective emboli.

Figure 14.25 Subacute bacterial endocarditis in a patient with a prosthetic heart valve. Small vasculitic lesions of this type are common with this type of immune complex disease, and may be quite subtle. Histologically, the features are of a non-specific, small-vessel leukocytoclastic vasculitis.

Figure 14.26 Subacute bacterial endocarditis (SBE) in the same patient as shown in Figure 14.25. Conjunctival lesions, as shown here, and retinal vasculitis are uncommon in Henoch–Schönlein purpura or drug-related small-vessel vasculitis, and support a presumed diagnosis of SBE. Examination of fundi is diagnostically important in this disorder.

Figure 14.27 Subacute bacterial endocarditis demonstrating an Osler node of the finger pulp. These lesions may be embolic, as they have recently been demonstrated to contain bacteria.

Erythema elevatum diutinum

This disorder is rare in the UK but may be more common in the USA . Some cases are associated with araproteinemias, usually of IgA type. Histologically, there is a leukocytoclastic vasculitis with mixed inflammatory infiltrate that may contain neutrophils, eosinophils, and plasma cells.

    Lesions are purplish and sometimes purpuric, often with discoid or annular morphology and a yellowish margin. They tend to occur over bony prominences of the hands, knees (Fig. 14.28), and face. Older lesions are more brown. Variation in intensity in relation to temperature change and premenstrual exacerbations may occur.

    Treatment is usually with topical corticosteroids or systemic dapsone.

Figure 14.28 Erythema elevatum diutinum. Old lesions may be quite large and fibrotic, as shown here. The knees and other bony prominences are a common site. (Courtesy of Gary W. Cole, M.D.)

Granuloma faciale

This disorder occurs typically on the face, but is actually vasculitic rather than granulomatous. Lesions are (usually solitary) brownish plaques (Fig.14.29), which have a benign behavior. Dapsone is usually recommended to treat this process, but some cases respond fully to strong topical steroids or intralesional steroid.

Figure 14.29 Granuloma faciale, which has a typical brown and rather granulomatous appearance. Histologically, this has mild vasculitic features.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.