| disease | Polyarteritis Nodosa |
| alias | Polyarteritis Nodosa |
Polyarteritis nodosa is a necrotizing vasculitis involving inflammation of the small and medium-sized arteries. Clinical manifestations vary depending on the affected vessels, ranging from skin-limited (cutaneous type) to multi-organ or systemic involvement (systemic type). The most commonly affected organs include the kidneys, heart, nervous system, and skin.
bubble_chart Etiology
It has not yet been clarified. Many data suggest a close relationship between viral infection and nodular poly stirred pulse itis, with 30–50% of patients accompanied by hepatitis B virus infection. The detection of hepatitis B surface antibody (HTLV-1), human immunodeficiency virus (HIV), and others in the serum may also be associated with vasculitis. Viral antigens and antibodies form immune complexes that deposit in the vascular wall, leading to necrotizing stirred pulse itis.
Drugs such as sulfonamides, penicillin, and others, as well as serum injections, can also serve as disease causes for this condition. Tumor antigens can induce immune complexes, leading to vasculitis. A small number of patients with hairy cell leukemia develop this disease after the illness, and there are reports linking cutaneous nodular poly stirred pulse itis to segmental ileum itis.
In summary, the disease cause of this condition is multifactorial, and its onset is related to immune dysregulation. The above factors lead to damage to vascular endothelial cells, releasing large amounts of chemokines and cytokines, such as interleukin (IL-1) and tumor necrosis factor (TNF), which exacerbate endothelial cell injury. Anti-neutrophil cytoplasmic antibodies (ANCA) can also injure vascular endothelium, impairing its ability to regulate blood vessels, leaving the vessels in a state of spasm and resulting in ischemic changes, thrombosis, and vascular occlusion.
bubble_chart Pathological ChangesIt primarily affects small and medium-sized arteries, characterized by segmental full-thickness necrotizing vasculitis, often occurring at arterial bifurcations. Occasionally, it may involve adjacent veins. Various organs can be affected, with the kidneys, heart, brain, and gastrointestinal tract being the most common, while the lungs and spleen are less frequently involved. The pathological progression includes: initial stage [first stage]—subendothelial edema, fibrin exudation, endothelial cell detachment, followed by fibrinoid necrosis in the medial layer, swelling, degeneration, and necrosis of muscle fibers. The entire vessel wall may be infiltrated by neutrophils, monocytes, lymphocytes, and eosinophils, leading to disruption of the internal elastic lamina and possible formation of small aneurysms. Due to intimal thickening and thrombosis, the lumen narrows, causing ischemia in the supplied tissues. As inflammation gradually subsides, fibrous tissue proliferates, thickening the vessel wall or even leading to occlusion. The inflammatory process gradually resolves, with the disrupted medial layer and internal elastic lamina being replaced by fibrous connective tissue, resulting in organization. These various pathological changes often coexist in the same patient.
bubble_chart Clinical Manifestations
Both males and females can be affected, with males being more commonly affected. Since multiple tissues and organs can be involved, the clinical manifestations are complex and diverse. In the early stages of the disease, atypical systemic symptoms are more common, or it may primarily manifest in one system or organ. Generally, the disease is divided into cutaneous and systemic types.
(1) Cutaneous Type: Lesions are confined to the skin, with nodules being the most characteristic and common feature. These nodules are typically 0.5–1.0 cm in size, firm, single or multiple, arranged along superficial arteries or irregularly clustered near blood vessels. They appear rose-red, bright red, or nearly normal skin-colored, may be freely movable or adherent to the overlying skin, and are tender. The center of the nodules may necrose and form ulcers, with irregular edges, often accompanied by livedo reticularis, wheals, blisters, and purpura. They commonly occur on the legs, forearms, trunk, face, scalp, and earlobes, appearing bilaterally but asymmetrically. The lesions can also be polymorphic. Generally, there are no systemic symptoms, though low-grade fever, arthralgia, myalgia, and other discomforts may occur. The course is benign, with intermittent episodes.(2) Systemic Type: The onset may be acute or insidious, often accompanied by irregular fever, weakness, arthralgia, myalgia, weight loss, and other systemic discomforts.
1. Renal involvement is the most common, presenting with proteinuria, hematuria, and, in a few cases, nephrotic syndrome. Extensive involvement of intrarenal arteries can lead to severe renal impairment. Rupture of intrarenal arterial aneurysms or infarction may cause severe renal colic and massive hematuria. Hypertension is relatively common and may sometimes be the sole clinical manifestation. Hypertension exacerbates renal damage, and uremia is one of the main causes of death in this disease.
2. Digestive system involvement varies depending on the affected site, with abdominal pain being the most common symptom. Other symptoms may include vomiting and hematochezia. Rupture of small arterial aneurysms can lead to gastrointestinal or intra-abdominal bleeding, presenting as severe abdominal pain, signs of peritonitis. Liver involvement may manifest as jaundice, upper abdominal pain, and elevated transaminases. Some cases may also involve chronic active hepatitis due to concurrent hepatitis B virus infection. Involvement of the gallbladder or pancreas may present as symptoms of acute cholecystitis or acute pancreatitis.
3. The cardiovascular system is also frequently affected. Apart from renal hypertension impacting the heart, coronary arteritis can cause angina pectoris, and severe cases may lead to myocardial infarction or heart failure. Various arrhythmias may occur, with supraventricular tachycardia being common. Heart failure is also one of the main causes of death in this disease.4. Both the peripheral and central nervous systems may be involved, with peripheral neuropathy being more common, presenting as sensory abnormalities, motor disturbances, mononeuritis multiplex, or polyneuropathy. Central nervous system involvement may cause dizziness, headache, and, in cases of cerebral artery thrombosis or aneurysm rupture, hemiplegia. Spinal cord involvement is rare.
5. Skin lesions resemble those seen in the cutaneous type, with some patients exhibiting Raynaud’s phenomenon.
6. Pulmonary vascular involvement is rare, and ocular symptoms occur in about 10% of cases. Other systems, such as the reproductive system, may show involvement in autopsy findings (e.g., 80% of testes and epididymis), but clinical manifestations occur in only about 20% of cases.
The course of the disease varies depending on the organs involved and the severity. Severe cases progress rapidly and may even be fatal. Others may experience alternating periods of remission and relapse, persisting for years before eventual recovery.
bubble_chart Auxiliary Examination
1. The total white blood cell count and neutrophils are often elevated. There may be varying degrees of anemia due to loss of blood or renal insufficiency. The erythrocyte sedimentation rate is usually increased. Urinalysis commonly reveals proteinuria, hematuria, and casts. When renal damage is severe, serum creatinine increases and creatinine clearance decreases.
2. Immunological tests: Gamma globulin is elevated, while total complement and C3 complement levels are often decreased, reflecting disease activity. Rheumatoid factor and antinuclear antibodies may be positive or weakly positive. ANCA is occasionally positive. Approximately 30% of cases test positive for HBsAg.
3. Pathological biopsy is of great significance for diagnosis. However, since the lesions are segmentally distributed, selecting the appropriate organ and site for biopsy is crucial. Findings may include small- and medium-sized stirred pulse necrotizing vasculitis.
If biopsy is difficult or yields negative results, angiography can be performed. This often reveals aneurysmal dilation or segmental stenosis of small- and medium-sized stirred pulses in the kidneys, liver, mesenteric membrane, and other internal organs, which is of significant diagnostic value.
The cutaneous type is primarily diagnosed based on skin lesion manifestations, especially subcutaneous nodules distributed along superficial {|###|}stirred pulse{|###|}, polymorphic lesions, and, when necessary, a skin biopsy can confirm the diagnosis.
The systemic type involves widespread systems and presents with diverse clinical manifestations, with no unified diagnostic criteria. The 1990 standards proposed by the American Bi Disease Association can serve as a reference: ① Weight loss of ≥4kg since onset. ② Livedo reticularis of the skin. ③ Exclusion of testicular pain or tenderness due to infection, trauma, or other causes. ④ Myalgia, weakness, or tenderness in the lower limbs. ⑤ Mononeuritis or polyneuropathy. ⑥ Diastolic blood pressure ≥12.0kPa (90mmHg). ⑦ Elevated creatinine or blood urea nitrogen levels. ⑧ HBsAg or HBsAb (+). ⑨ {|###|}stirred pulse{|###|} angiography reveals visceral {|###|}stirred pulse{|###|} infarction or aneurysm formation (excluding {|###|}stirred pulse{|###|} sclerosis, fibromuscular dysplasia, or other non-inflammatory causes). ⑩ Biopsy of small- or medium-sized {|###|}stirred pulse{|###|} shows granulocytes or mononuclear cell infiltration in the vessel wall. The presence of at least 3 of these 10 criteria suggests polyarteritis nodosa. Among these, biopsy and angiographic abnormalities are particularly significant diagnostic evidence.
bubble_chart Treatment Measures
This disease can be caused by various {|###|}disease causes{|###|}. Avoid drug abuse to prevent drug allergies and infections, with hepatitis B virus infection being particularly significant.
Corticosteroids are the first-line treatment for this disease. Untreated cases have a poorer prognosis, and early use can improve outcomes. For mild cases without severe visceral damage, glucocorticoids alone are used for treatment, such as prednisone at 1mg/(kg·d) orally. For severe cases with poor response to hormone therapy after one month, cytotoxic drugs such as cyclophosphamide, azathioprine, or methotrexate may be combined. Cyclophosphamide is the most effective and commonly used, with a typical dose of 2mg/(kg·d) orally. If gastrointestinal side effects are intolerable, intravenous administration may be used. Clinically, the combination of hormones and cyclophosphamide yields better results. Satisfactory efficacy has even been achieved in cases with hypertension and nephropathy. Thrombosis is common in this disease, and the addition of non-steroidal anti-inflammatory and anticoagulant drugs such as enteric-coated aspirin or dipyridamole provides considerable symptomatic relief. If vascular stenosis occurs, vasodilators such as calcium channel blockers may be used.
Allergic granulomatosis requiring differential diagnosis often presents with asthma clinically, involving both the upper and lower respiratory tracts. It primarily affects small arteries, arterioles, and veins, with features such as necrotizing granulomas and various cellular infiltrations, particularly eosinophils. Patients with allergic vasculitis often have a history of drug allergies or vaccinations, mainly affecting the skin and potentially complicating with myocarditis or interstitial nephritis, primarily involving small arteries and veins. Pathologically, leukocytoclasis or lymphocyte infiltration is observed, occasionally with granuloma formation. Polyarteritis nodosa accompanied by fever and weight loss should be differentiated from infectious diseases. The presence of heart murmurs requires differentiation from subacute bacterial endocarditis. Many diseases, such as systemic lupus erythematosus and rheumatoid arthritis, may be complicated by polyarteritis and require careful differentiation.
