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POLYARTERITIS NODOSA

PAN is a rare disease. In a study that considered biopsy-proven forms only, the annual incidence and prevalence of the disease were, respectively, 0.7 per 100,000 and 6.3 per 100,000 habitants polyarteritis nodosa, poliarteritis. Estimates of the annual incidence for PAN-type systemic vasculitis in

In some cases, PAN is the consequence of HBV infection.  In France, HBV-related PAN formerly accounted for one third (36%) of all cases of systemic PAN, but we have noted a progressive decrease in the number of cases since the development of vaccines against viral hepatitis. Only 7% of the cases of PAN were attributable to HBV infection. HBV-related vasculitis almost always takes the form of

The clinical symptoms are the same as those observed in the other cases of PAN except for orchitis, which is more frequent in this group. Other etiologies have been found in some PAN patients: human immunodeficiency virus (HIV), cytomegalovirus, parvovirus B 19, human T-lymphotropic virus type I, and hepatitis C virus (HCV).

Histopathologic Analyses

Vasculitis can be demonstrated in various organs. Nerve and muscle are the most frequent sites for biopsy. Diagnosis of vasculitis by nerve biopsy has difficulties linked to sampling. Limited biopsies of the distal portion of a sensory nerve, such as the sural nerve, may not show diagnostic features. To improve the contribution of the nerve biopsy, the sample should include a

Many controversies surround the classification of vasculitis. To the best of our knowledge, even the definition of vasculitis itself has not met with full consensus. Vasculitis may be considered any inflammatory vascular disease able to induce ischemic tissue

Lesions similar or identical to those of PAN may be observed in nerves of patients with rheumatoid arthritis, Sjogren's syndrome, cryoglobulinemia, WG, and CSS. Some of the criteria used for the classification of systemic vasculitides listed previously are not operative in nerve pathology. For example, typical histopathologic features of CSS include necrotizing vasculitis affecting both arteries and veins, tissue eosinophilic infiltration, and extravascular granulomas with central necrosis and epithelioid cells. These findings, however, largely derive from autopsy studies, and nerve biopsies, at best, disclose necrotizing vasculitis with eosinophils in the infiltrate and no extravascular granuloma.

Systemic PAN may be associated with leukocytoclastic vasculitis, another vasculitis likely due to immune complex deposition that affects small vessels, mainly postcapillary venules. Leukocytoclastic vasculitis is seldom observed in peripheral nerves; and is mainly seen in skin. Errors may occur when a skin biopsy is used to classify systemic necrotizing vasculitis, and the use of

Initial symptoms vary from case to case. The majority of patients present at onset with constitutional symptoms, eg, malaise, fever, and weight loss, associated with pain resulting from peripheral neuropathy, musculoskeletal, GI, or cutaneous involvement.

Mononeuritis multiplex was, in our series of 182 cases of PAN, the most frequent finding (70%) and often the initial symptom in the literature. Motor and sensory signs are typically asymmetrical, predominantly

Musculoskeletal Involvement

Myalgias are frequent (30%-73%) and can be intense and accompanied by muscle tenderness. They are often a presenting symptom of the disease. Creatine kinase levels are usually normal. Arthralgias, present in 46.2% of the cases, are often

Skin involvement is present in 25% to 60% of the patients with systemic PAN. ^[35] Vascular purpura is typically papulopetechial, sometimes bullous or vesiculous. Infiltration is inconstant, but when present, is the ideal site for

According to the type of involvement, it is possible to diagnose two different diseases: MPA when glomerulonephritis is observed, and PAN when vascular nephropathy is responsible for renal failure. Vascular nephropathy is the usual manifestation described in PAN. It develops rapidly and is the consequence of multiple renal infarcts. When present, malignant hypertension is

Gastrointestinal Involvement

GI tract involvement is one of the most severe manifestations of PAN. Abdominal pain was noted in 34% of our patients. Digestive bleeding and bowel perforation can occur. Intractable abdominal pain associated with weight loss is the 

Cardiac manifestations may be due to vasculitis of the coronary arteries, their branches, or to severe or malignant hypertension. In our experience, despite coronary artery vasculitis, angina is rare and coronary angiography is usually normal. Cardiomegaly

Orchitis is a classic symptom of PAN and is one of the American College of Rheumatology criteria for its diagnosis. Breast and uterine PAN have also been described. Ocular manifestations include retinal vasculitis, retinal detachment, and 

Sometimes, PAN appears to be limited to one organ without detectable systemic involvement. Organs involved are appendix, gallbladder, bowel, uterus, or testis. Isolated peripheral neuropathy is not unusual. Cutaneous forms of PAN are well known and

Treatment 

Conduction block may occasionally be seen in patients with vasculitic neuropathy.  This finding is important because it suggests that nerve ischemia has produced demyelination or functional disruption of conduction without frank nerve infarction. This view is supported by experimental models of subinfarctive ischemic nerve damage and the histologic studies of ischemic neuropathy in