Polyarteritis nodosa = التهاب الشرايين العقد |
Cutaneous Polyarteritis Nodosa
Cutaneous polyarteritis nodosa is a vasculitis involving the arteries and arterioles of the septa of the subcutaneous fat with little or no evidence of systemic disease.The lower legs are usually affected. Clinically, the lesions consist of bilateral, tender erythematous nodules, which may undergo ulceration, and a background of livedo reticularis . “Starburst” livedo is characteristic and marks a cluster of nodular lesions. Mild constitutional symptoms, including low-grade fever, arthralgias, myalgias, malaise, and fatigue, may appear simultaneously with the cutaneous lesions. The absence of systemic involvement is characteristic and, although the course may be prolonged, the prognosis is good. In rare instances, patients with cutaneous polyarteritis nodosa show serologic evidence of hepatitis B infection, cryoglobulinemia, or peripheral neuropathy. Histopathologically, cutaneous lesions show vasculitis involving medium-sized arteries and arterioles at the septa and sometimes lobules of the upper subcutis. Involvement of the arterioles of the lobule may also be seen with microscopic polyangiitis. The involved vessel has a thickened wall and an inflammatory infiltrate of variable composition, depending on the stage of evolution of the lesions. Characteristically, the intima of the involved artery exhibits an eosinophilic ring of fibrinoid necrosis, giving a target-like appearance to the vessel. Although luminal thrombi may be present, they are less frequent than in lesions of superficial thrombophlebitis. Direct immunofluorescent studies of lesions of cutaneous polyarteritis nodosa have shown immunoglobulin M and complement deposition in the involved vessel walls. As is the case in superficial thrombophlebitis, lesions of cutaneous polyarteritis nodosa show little or no involvement of the adjacent fat lobule, and the process is exclusively a septal arteritis. Mild cases of cutaneous polyarteritis nodosa may be managed with nonsteroidal anti-inflammatory drugs or low doses of prednisone. In patients with acute flare-ups of cutaneous polyarteritis nodosa associated with documented bacterial infections, a long course of treatment with antibiotics may be helpful.
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