BUENOS AIRES — A positive test for antineutrophil cytoplasmic antibody may be associated with a vasculitis of the skin, but the test is usually not specific, so patients with other diseases may test positive, Dr. Jeffrey Callen said at the 21st World Congress of Dermatology.
To support a diagnosis of one of the ANCA-associated vasculitides, a positive ANCA test should be correlated with other clinical symptoms. “Skin disease is a relatively common feature in ANCA-associated vasculitis and can be an initial manifestation,” said Dr. Callen of the University of Louisville (Ky.).
ANCA-associated vasculitis affects small- to medium-sized vessels. The traditional ANCA-associated vasculitides are Wegener's granulomatosis, microscopic polyarteritis, and Churg-Strauss syndrome. Wegener's granulomatosis and microscopic polyarteritis are both characterized by pauci-immune necrotizing vasculitis with crescentic glomerulonephritis and pulmonary capillaritis. A significant difference between the two is the presence of granulomas in Wegener's patients.
Churg-Strauss syndrome is a systemic vasculitis often tied to eosinophilia, allergic rhinitis, and asthma. Drug-induced vasculitides, like minocycline-induced disease, are also sometimes ANCA positive, he said.
ANCAs are autoimmune antibodies directed against antigens in the cytoplasmic granules of neutrophils and monocytes. Most are IgG associated. They are grouped according to histochemical staining: cytoplasmic-ANCA (c-ANCA) and perinuclear-ANCA (p-ANCA). C-ANCA against proteinase 3 is specific for Wegener's. One of the major p-ANCAs, directed against myeloperoxidase, is seen in microscopic polyarteritis but is also found in ulcerative colitis, Sweet's syndrome, propylthiouracil-induced vasculitis, and minocycline-induced vasculitis, said Dr. Callen.
Skin lesions, primarily ulcerations and palpable purpura, are a common feature of microscopic polyarteritis, and cutaneous manifestations have been reported in up to 70% of patients with Churg-Strauss syndrome. Skin lesions in Churg-Strauss include subcutaneous nodules and macular or papular erythema or urticaria, but the most common is palpable purpura, seen in about half of the patients who have cutaneous manifestations. Other possible cutaneous manifestations include ulceration and livedo reticularis. A Churg-Strauss granuloma on the skin is quite rare but highly specific, Dr. Callen said.
In a review of 90 patients with Churg-Strauss syndrome at the Mayo Clinic between 1976 and 1995, investigators found 36 (40%) had cutaneous manifestations (J. Am. Acad. Dermatol. 1997;37:199-203), most frequently purpura and petechiae on the lower extremities and cutaneous nodules and papules on the elbows.
Wegener's granulomatosis skin lesions are similar to those in Churg-Strauss syndrome. In addition, pyoderma gangrenosum-like lesions can occur in Wegener's. A recent report described cutaneous manifestations of Wegener's in 17 patients (J. Cutan. Pathol. 2007;34:739-47). Three had skin disease before systemic disease; one patient's ANCA test was initially negative. Six had concurrent onset of skin and systemic disease, and eight developed skin disease after systemic disease was diagnosed.
In a meta-analysis (JAMA 2007;298:655-69), patients with localized disease were recommended an antibiotic like cotrimoxazole, with or without corticosteroids. Methotrexate plus corticosteroids was recommended for generalized, non-organ-threatening disease and pulse cyclophosphamide plus corticosteroids was touted for patients with generalized, organ-threatening disease. For severe renal vasculitis, plasma exchange might also be included. High-dose cyclophosphamide plus pulse methylprednisolone was recommended for diffuse pulmonary hemorrhage, possibly with plasma exchange.
Dr. Callen has consulted for and accepted speaker fees from several makers of biologics used in rheumatic diseases.