, David G. I. Scott2 and Chetan Mukhtyar2
Department of Rheumatology, Ipswich Hospital NHS Trust, Ipswich, UK
Department of Rheumatology, Norfolk and Norwich University Hospital, Norwich, UK
Polyarteritis nodosa (PAN) is a rare medium vessel vasculitis that is often associated with Hepatitis B Virus (HBV-PAN) infection. It was first described by Kussmaul and Meier in 1866, in a patient with palpable cutaneous nodules.
10.2 Definition and Classification
The Chapel Hill Consensus Conference in 1994 defined cPAN as “Necrotizing inflammation of medium-sized or small arteries without glomerulonephritis or vasculitis in arterioles, capillaries, or venules; and not associated with ANCA” . The ACR in 1990 developed classification criteria that are widely used in clinical trials (Table 10.1) . The criteria have a sensitivity of 82.2 % and specificity of 86.6 %. There are no validated diagnostic criteria.
ACR (1990) classification criteria for PAN
Loss of 4 kg or more of body weight since the illness began, not due to dieting or other factors
Mottled reticular pattern over the skin of portions of the extremities or torso
Testicular pain or tenderness
Pain or tenderness of the testicles, not due to infection, trauma, or other causes
Myalgias, weakness, or leg tenderness
Diffuse myalgias (excluding shoulder or hip girdle) or weakness of muscles or tenderness of leg muscles
Mononeuropathy or polyneuropathy
Development of mononeuropathy, multiple mononeuropathies, or polyneuropathy
Diastolic BP >90 mmHg
Development of hypertension with diastolic BP >90 mmHg
Elevated blood urea or creatinine
Elevated BUN >40 mg/dL or creatinine 1.5 mg/dL, not due to dehydration or obstruction
Hepatitis B virus (HBV)
Presence of hepatitis B surface antigen or antibody in serum
Arteriogram showing aneurysms or occlusion of the visceral arteries, not due to arteriosclerosis, fibromuscular dysplasia, or other noninflammatory causes
Biopsy of small or medium vessel
Histological changes showing the presence of sized artery containing PMN granulocytes or granulocytes and mononuclear leucocytes in the artery wall
PAN as defined by the CHCC is very rare with an annual incidence of <1/million . In areas endemic for HBV, incidence rates of up to 77/million have been recorded. PAN occurs at all ages and is more common in men. The incidence of HBV-PAN has been falling due to increased vaccination against HBV and screening of blood products for HBV infection. The most common cause now is drug abuse.
The etiology of PAN is unknown. There is clear evidence that in HBV the formation of immune complexes containing HBsAg is the triggering factor. ANCA and other autoantibodies are not found in PAN suggesting that it is not a classical autoimmune disease. No clear HLA associations have been established.
10.5 Clinical Features
The spectrum of disease severity is broad ranging from mild, limited disease to progressive disease, which may be fatal. Virtually any organ may eventually be affected. The clinical features of PAN and HBV-PAN are similar [4, 5].
Typically, the patient experiences constitutional features of fever, malaise, weight loss, and diffuse aching, along with manifestations of multisystem involvement such as peripheral neuropathy and an asymmetric polyarthritis. Visceral involvement, such as the kidney or gut, may present coincidentally with these features or may appear later.
Cutaneous lesions include infarctions, ulcerations, livedo reticularis, subcutaneous nodules, and ischemic changes of the distal digits (Fig. 10.1) and occur in 25–60 % of patients.
Digital ischemia in patient with polyarteritis nodosa
Arthralgia or arthritis is present in as many as 50 % of patients. A polymyalgic syndrome may occur at presentation. An asymmetric, episodic, nondeforming polyarthritis involving the larger joints of the lower extremity may occur in up to 20 % of cases, most commonly early in the disease.
Peripheral neuropathy may occur in up to 70 % of cPAN and may be the initial manifestation. The neuropathy affects the lower extremities somewhat more often than the upper extremities. The onset is often very acute, with pain and paresthesias radiating in the distribution of a peripheral nerve, followed in hours by a motor deficit of the same peripheral nerve. This may progress asymmetrically to involve other peripheral nerves and produce a mononeuritis multiplex or a multiple mononeuropathy. With additional nerve damage, the final result may be a symmetric polyneuropathy involving all sensory modalities and motor functions. CNS involvement is much less common and includes headache, seizures, cranial nerve dysfunction, cerebral hemorrhage, and stroke.
PAN is usually characterized by vascular nephropathy, without glomerulonephritis in about 35 % of patients. Multiple renal infarcts, the consequence of vascular nephropathy, produce renal failure. Renal angiography will frequently show several aneurysms and infarcts. Ureteral stenosis and perinephric hematomas (microaneurysm rupture) can occur. Hypertension develops as a result of renal artery or, less commonly, renal parenchymal involvement. Hypertension, usually mild, occurs in 21–33 % of patients and is particularly associated with hepatitis B infection.