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- Subacute onset of constitutional complaints (eg, fever, weight loss, malaise, arthralgias), lower extremity nodules and ulcerations, mononeuritis multiplex, and intestinal angina (postprandial pain caused by the involvement of mesenteric vessels).
- Cutaneous polyarteritis nodosa (PAN) is a variant of the systemic disease in which vasculitis is limited to the skin, usually presenting as nodules that break down into ulcers.
- Angiogram or biopsy of an involved organ required for diagnosis.
- Angiography may reveal microaneurysms in the kidneys or gastrointestinal tract.
- Biopsies of the skin and peripheral nerves (with sampling of the adjacent muscle) are the least invasive ways of confirming the diagnosis histopathologically.
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Classic PAN is characterized by necrotizing inflammation of muscular arterioles and medium-sized arteries that spares the smallest blood vessels (eg, capillaries). PAN is not associated with glomerulonephritis, although it can cause renovascular hypertension and renal infarctions through its involvement of the medium-sized intrarenal vasculature. Features that distinguish PAN from other forms of systemic vasculitis are confinement of the disease to the arterial as opposed to the venous circulation, the sparing of the lung, and the absence of granulomatous inflammation.
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Reported annual incidence rates of PAN range from 2 to 9 cases per million people per year. A higher incidence (77 cases/million) was reported in an Alaskan area hyperendemic for hepatitis B virus (HBV). With the availability of the HBV vaccine, however, the percentage of cases associated with HBV has declined substantially (now <10% of all cases in the developed world). PAN appears to affect men and women with approximately equal frequencies and to occur in all ethnic groups.
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PAN can involve virtually any organ system with the exception of the lungs. The disease demonstrates a predilection for certain organs, particularly the skin, peripheral nerves, gastrointestinal tract, and kidneys. A nearly universal complaint among patients is some type of pain, caused by myalgias, arthritis, peripheral nerve infarction, testicular ischemia, or mesenteric vasculitis.
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Constitutional Symptoms
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Fevers are a common feature of PAN. The characteristics of the fever vary substantially among patients, ranging from periods of low-grade temperature elevation to spiking febrile episodes accompanied by chills (patterns of low-grade fever are more common than are hectic fevers). Tachycardia with or without fever may be another feature of PAN. Malaise, weight loss, and myalgias are also common.
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Vasculitis of medium-size arteries may produce several types of skin lesions. These cutaneous findings include livedo racemosa (Plate 48), nodules, papules, ulcerations, and digital ischemia leading to gangrene. All of these findings or combinations of them may occur in the same patient. The livedo racemosa (often termed “livedo reticularis”), which may have a diffuse distribution over the extremities and buttocks, does not blanch with the application of pressure to the skin. Nodules, papules, and ulcers tend to occur on the lower extremities, particularly near the malleoli, in the fleshy parts of the calf, and over the dorsal surfaces of the feet. Nodules frequently evolve into ulcerations that have scalloped borders (Figure 35–1) ...