Polyarteritis nodosa
Polyarteritis nodosa is a rare, antineutrophil cytoplasmic antibody (ANCA)-negative necrotizing vasculitis of medium and small arteries that spares the lungs and spares glomeruli, presenting with constitutional illness, mononeuritis multiplex, livedo reticularis, mesenteric ischemia, and renovascular hypertension. Diagnosis rests on biopsy or mesenteric/renal angiography, and treatment is glucocorticoids plus cyclophosphamide for severe idiopathic disease, or a short glucocorticoid course with antiviral therapy and plasma exchange when hepatitis B-associated.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
Definition: polyarteritis nodosa (PAN) is a rare systemic necrotizing vasculitis of medium-sized, and sometimes small, arteries producing segmental transmural inflammation, aneurysmal dilation, and…
- Epidemiology
Rare disease: prevalence is approximately 31 per million and has been declining.
- Risk factors
Hepatitis B virus infection: historically the strongest identified association, and it changes the treatment strategy entirely when present.
- Pathophysiology
Segmental transmural necrotizing inflammation: PAN attacks medium-sized, and sometimes small, muscular arteries in a patchy, segmental pattern sparing veins, arterioles, capillaries, and venules…
- Clinical features
Constitutional symptoms (about 65%): fever, malaise, and weight loss, often the presenting complaint before an organ pattern emerges.
- Differential diagnosis
Microscopic polyangiitis: the closest mimic; unlike PAN it is ANCA-positive (usually myeloperoxidase-ANCA), affects small vessels, and causes pulmonary-renal syndrome with glomerulonephritis and…
- Diagnosis
The American College of Rheumatology 1990 classification criteria establish the pattern: vasculitis is classified as PAN when at least 3 of these 10 are present (82% sensitivity, 87% specificity)…
- Management
First, screen for hepatitis B before choosing a strategy, since HBV status determines the entire pathway.
- Complications
Bowel infarction and perforation: the most life-threatening gastrointestinal complication, requiring emergent surgical evaluation.
- Prognosis
Treatment transforms outcomes: untreated PAN carries a poor prognosis, but the 5-year survival rate with treatment exceeds 80%.
- Prevention
Hepatitis B vaccination is the single most effective preventive measure against this driver: the HBV-attributable share of PAN fell from about 36% to under 5% after vaccination became widespread.
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Microscopic polyangiitis
Microscopic polyangiitis (MPA) is a pauci-immune small-vessel vasculitis, almost always with perinuclear antineutrophil cytoplasmic antibody (p-ANCA) targeting myeloperoxidase (MPO), that causes rapidly progressive crescentic glomerulonephritis and pulmonary alveolar hemorrhage without the granulomas, eosinophilia, or upper-airway disease of its ANCA-associated siblings. Diagnosis combines urine microscopy, ANCA serology, and biopsy, and treatment is glucocorticoids plus rituximab or cyclophosphamide induction followed by rituximab or azathioprine maintenance.
- Granulomatosis with polyangiitis
Granulomatosis with polyangiitis (GPA) is an antineutrophil cytoplasmic antibody (ANCA)-associated necrotizing granulomatous vasculitis of the upper airway, lower airway, and kidney, most often with cytoplasmic ANCA (c-ANCA) targeting proteinase 3 (PR3). Diagnosis rests on the clinical triad, ANCA serology, and tissue biopsy showing pauci-immune vasculitis, and treatment begins with high-dose glucocorticoids plus rituximab or cyclophosphamide for organ-threatening disease, followed by rituximab or azathioprine maintenance.
- Vasculitis: an overview
Vasculitis is inflammation and necrosis of blood vessel walls, classified by the Chapel Hill scheme into large, medium, small (ANCA-associated versus immune-complex), and variable-vessel disease, each with a vessel-size-predicted clinical syndrome. Diagnosis requires excluding mimics such as infective endocarditis and cholesterol embolization before confirming with serology and biopsy, and treatment is glucocorticoid induction plus cyclophosphamide or rituximab for organ-threatening disease.
- Hepatitis B virus (HBV) infection
Hepatitis B virus is a bloodborne and sexually transmitted DNA virus that causes acute hepatitis and, when infection becomes chronic, progresses through immune-tolerant, immune-active, immune-control, and reactivation phases toward cirrhosis and hepatocellular carcinoma. Diagnosis rests on hepatitis B serology, chronic infection is treated with entecavir or tenofovir, and reactivation during immunosuppression is prevented with prophylactic antiviral therapy.
- Cryoglobulinemia
Cryoglobulinemia is the presence of immunoglobulins that precipitate below 37 degrees Celsius, classified as type I (monoclonal, driven by a lymphoproliferative disorder, causing hyperviscosity) or mixed types II/III (immune-complex, driven mainly by hepatitis C virus infection, causing small-vessel vasculitis). Type I is treated by targeting the underlying clonal disorder; mixed disease is treated with direct-acting antiviral therapy for hepatitis C, escalating to glucocorticoids plus rituximab for organ-threatening vasculitis.