Vasculitis and the reactive erythemas

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Vasculitis and the reactive erythemas

Vasculitis and the reactive erythemas are characterized by inflammation within or around blood vessels. This may result from a type III hypersensitivity response, with circulating immune complexes, but other mechanisms are also possible.

Vasculitis

Vasculitis is a disease process usually centred on small or medium-sized blood vessels. It is often due to circulating immune complexes (CICs).

Aetiopathogenesis

The CICs, which may be associated with several conditions (Table 1), lodge in the vessel wall where they activate complement and cytokine release, attract polymorphs and damage tissue. Inflammatory cells infiltrate vessels. Endothelial cells may show swelling, fibrinoid change or necrosis.

Table 1 Causes of vasculitis

Group	Example
Idiopathic	50% of cases (no cause found)
Blood disease	Cryoglobulinaemia
Connective tissue disease	Systemic lupus erythematosus, rheumatoid arthritis
Drugs	Antibiotics, diuretics, non-steroidals, anticonvulsants, allopurinol, cocaine
Infections	Hepatitis B, streptococci, Mycobacterium leprae, Rickettsia
Neoplasia	Lymphoma, leukaemia
Other	Wegener’s granulomatosis, giant cell arteritis, polyarteritis nodosa

Clinical presentation

This depends on the size and site of the vessels involved. Vasculitis may be confined to the skin, or may be systemic and involve the joints, kidneys, lungs, heart, gut and nervous system. The skin signs are of palpable purpura, often painful and usually on the lower legs or buttocks (Fig. 1). Specific types are as follows:

Henoch–Schönlein purpura describes these signs, with arthritis, abdominal pain and haematuria. Direct immunofluorescence studies on a skin biopsy will show the small vessel immunoglobulin (Ig) A–CIC vasculitis, which can be helpful diagnostically. Mainly affects children and often follows a streptococcal infection.

Nodular vasculitis, characterized by tender subcutaneous nodules on the lower legs, results when deeper dermal vessels are involved.

Polyarteritis nodosa is characterized by a necrotizing vasculitis in medium-sized arteries. It is uncommon and afflicts middle-aged men who, in addition to tender subcutaneous nodules along the line of arteries, may develop hypertension, renal failure and neuropathy.

Wegener’s granulomatosis is a rare but potentially fatal granulomatous vasculitis of unknown cause. Malaise, upper and lower respiratory tract necrosis, glomerulonephritis and, in 40% of cases, a cutaneous vasculitis are found. Classical antineutrophil cytoplasm antibodies (c-ANCA) directed at proteinase 3 (PR3) are present.

Giant cell arteritis affects medium-sized arteries in the elderly. Visual loss may result if prednisolone is withheld. Patients present with scalp tenderness due to temporal artery involvement that can progress to scalp necrosis.

Fig. 1 Vasculitis with purpura and impending skin necrosis.

In vasculitis, a skin biopsy is helpful along with tests to look for internal organ involvement. Other causes of purpura need exclusion.

Management

The cause is identified and remedied if possible. Some idiopathic cases settle with bed rest but, if lesions continue to develop and if internal organs are involved, treatment is indicated. Dapsone, 100 mg daily, is often effective for cutaneous vasculitis. Otherwise, prednisolone (sometimes with an immunosuppressive) is prescribed. Giant cell arteritis, polyarteritis nodosa and Wegener’s granulomatosis nearly always require oral steroids and immunosuppression.

Erythema multiforme

Erythema multiforme is an immune-mediated disease, characterized by target lesions on the hands and feet. It has a variety of causes (Table 2).

Table 2 Causes of erythema multiforme

Group	Cause
Idiopathic	50% of cases (no cause found)
Viral	Herpes simplex, hepatitis B, orf, adenovirus, mumps, Mycoplasma
Bacterial	Streptococci, Rickettsia
Fungal	Coccidioidomycosis, histoplasmosis
Drugs	Antibiotics, phenytoin, non-steroidals
Other	Lupus erythematosus (p. 80), pregnancy, malignancy

Aetiopathogenesis

Cell-mediated immunity seems to be involved. CICs are also present and can be demonstrated in blood vessels. No provoking factor is found in 50% of cases. On histology, the epidermis is necrotic and the dermis shows oedema, an inflammatory infiltrate and vasodilatation.

Clinical presentation

Typical target lesions, seen on the hands and feet, consist of red rings with central pale or purple areas, which may blister (Fig. 2). Involvement of the oral, conjunctival and genital mucosae is not uncommon and, if extensive, is known as erythema multiforme major. Crops of new lesions appear for 2–3 weeks. The differential diagnosis includes toxic erythema (p. 86), Stevens–Johnson syndrome, toxic epidermal necrolysis, Sweet’s disease, urticaria and pemphigoid. A biopsy is often helpful. Toxic epidermal necrolysis (p. 87) may sometimes represent erythema multiforme in a severe form.

Fig. 2 Erythema multiforme.

Target lesions are seen here on the dorsal aspect of the hand.

Management

Identification and treatment of the underlying cause is the ideal. Mild cases resolve spontaneously and require symptomatic measures only. Extensive involvement necessitates hospital admission for supportive therapy. Systemic steroids are often prescribed to moderate the acute symptoms, although it is debatable whether they affect the outcome.

Erythema nodosum

Erythema nodosum is a panniculitis (i.e. an inflammation of the subcutaneous fat) that usually presents as painful red nodules on the lower legs. It is believed to result from CIC deposition in vessels of the subcutis. Infection, drugs and some systemic diseases are underlying causes (Table 3).

Table 3 Causes of erythema nodosum

Group	Cause
Idiopathic	About 20% of cases
Bacterial	Streptococci, TB, leprosy, Yersinia, Mycoplasma, Salmonella
Fungal	Coccidioidomycosis, Trichophyton
Viral	Cat-scratch fever, chlamydiae
Drugs	Sulphonamides, oral contraceptives
Systemic disease	Inflammatory bowel disease, sarcoidosis, Behçet’s disease, malignancy (rare)

Clinical presentation

Deep, firm and tender reddish–blue nodules, 1–5 cm in diameter, develop on the calves (Fig. 3), shins and occasionally on the forearms. Joint pains and fever are common. Spontaneous resolution usually occurs within 8 weeks. Women are affected more than men (F : M ratio 3 : 1). Other causes of panniculitis (e.g. pancreatic disease, cold, trauma and lupus erythematosus), cellulitis and phlebitis need to be excluded. A skin biopsy is helpful. If tuberculosis or sarcoidosis is suspected, a chest radiograph and Mantoux test are indicated.

Fig. 3 Erythema nodosum of the lower leg.

Management

As spontaneous remission is usual, active therapy is rarely needed, although a non-steroidal anti-inflammatory drug, potassium iodide or dapsone may help.

Sweet’s disease

Sweet’s disease (acute febrile neutrophilic dermatosis) occurs as raised plum-coloured plaques on the face or limbs (Fig. 4), typically with fever and a raised neutrophil count. It is not a true vasculitis but results from polymorph infiltration of the dermis. Leukaemia, ulcerative colitis and other disorders may be associated and must be excluded. Drugs are another cause. Treatment with prednisolone is usually required.