Giant cell arteritis
Giant cell arteritis is also known as temporal arteritis, which is a systemic chronic inflammatory vascular disease with many characteristics similar to those of Takayasu disease. The histologic and pathologic changes and laboratory findings are similar. Patients tend to be white women older than 50 years, with a high incidence in Scandinavia and women of Northern European descent. Genetic factors may play a role in disease pathogenesis, with a human leukocyte antigen (HLA) variant having been identified. Differences exist between Takayasu and giant cell arteritis in terms of presentation, disease location, and therapeutic efficacy. The inflammatory process typically involves the aorta and its extracranial branches, of which the superficial temporal artery is specifically affected. The clinical syndrome begins with a prodromal phase of constitutional symptoms, including headache, fever, malaise, and myalgias. The patients may be initially diagnosed with coexisting polymyalgia rheumatica; an HLA-related association may exist between the two diseases. As a result of vascular narrowing and end-organ ischemia, complications may occur such as visual alterations, including blindness and mural weakness, resulting in acute aortic dissection that may be devastating. Ischemic optic neuritis resulting in partial or complete blindness occurs in up to 40% of patients and is considered a medical emergency. Cerebral symptoms occur when the disease process extends to the carotid arteries. Jaw claudication and temporal artery tenderness may be experienced. Aortic lesions are usually asymptomatic until later stages and consist of thoracic aneurysms and aortic dissections. The diagnostic gold standard is a temporal artery biopsy, which will show the classic histologic findings of multinucleated giant cells with a dense perivascular inflammatory infiltrate. Treatment regimens are centered on corticosteroids, and giant cell arteritis tends to rapidly respond. Remission rates are high, and treatment tends to have a beneficial and preventative effect on the development of subsequent vascular complications.
The disorder most likely involved in systemic small vessel vasculitis would be:
Classification of vasculitis based on vessel involvement:
The following is true regarding polyarteritis nodosa (PAN) EXCEPT:
Polyarteritis nodosa (PAN) is another systemic inflammatory disease process, which is characterized by a necrotizing inflammation of medium-sized or small arteries that spares the smallest blood vessels (ie, arterioles and capillaries). This disease predominantly affects men over women by a 2:1 ratio. PAN develops subacutely, with constitutional symptoms that last for weeks to months. Intermittent, low-grade fevers, malaise, weight loss, and myalgias are common presenting symptoms. As medium-sized vessels lie within the deep dermis, cutaneous manifestations occur in the form of livedo reticularis, nodules, ulcerations, and digital ischemia. Skin biopsies of these lesions may be sufficient for diagnosis. Inflammation may be seen histologically, with pleomorphic cellular infiltrates and segmental transmural necrosis leading to aneurysm formation. Neuritis from nerve infarction occurs in 60% of patients, and gastrointestinal complications occur in up to 50%. Additionally, renal involvement is found in 40% and manifests as microaneurysms within the kidney or segmental infarctions. Cardiac disease is a rare finding except at autopsy, where thickened, diseased coronary arteries may be seen, as well as patchy myocardial necrosis. Patients may succumb to renal failure, intestinal hemorrhage, or perforation. End-organ ischemia from vascular occlusion or aneurysm rupture can be disastrous complications with high mortality rates. The mainstay of treatment is steroid and cytotoxic agent therapy. Up to 50% of patients with active PAN will experience remission with high dosing.
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