From the Guidelines
Polyarteritis nodosa (PAN) is diagnosed based on a combination of clinical, laboratory, and imaging findings, with a focus on tissue biopsy or angiography as the gold standard for confirmation, as recommended by the 2021 American College of Rheumatology/Vasculitis Foundation guideline 1. The diagnostic criteria for PAN typically include a combination of the following features:
- Weight loss
- Livedo reticularis
- Testicular pain or tenderness
- Myalgias, weakness, or leg tenderness
- Mononeuropathy or polyneuropathy
- Diastolic blood pressure > 90 mmHg
- Elevated blood urea nitrogen or creatinine
- Hepatitis B virus infection
- Arteriographic abnormalities (aneurysms or occlusions of visceral arteries)
- Biopsy of small or medium-sized artery containing polymorphonuclear neutrophils According to the guideline, diagnosis is generally confirmed by tissue biopsy of an affected organ or angiography if tissue biopsy cannot be obtained, with typical histologic findings including mixed-cell inflammatory infiltrates in the vessel wall and fibrinoid necrosis, and an absence of granulomas and giant cells 1. The presence of these criteria, along with the exclusion of other vasculitides and connective tissue diseases, supports the diagnosis of PAN. Early diagnosis is crucial for timely treatment initiation, which typically involves corticosteroids and immunosuppressive agents to control inflammation and prevent organ damage. It's essential to note that while hepatitis B infection is associated with some cases of PAN, many cases are not, and ANCA (anti-neutrophil cytoplasmic antibodies) are typically negative in PAN, which helps distinguish it from other forms of vasculitis 1.
From the Research
Diagnostic Criteria for Polyarteritis Nodosa (PAN)
The diagnosis of Polyarteritis Nodosa (PAN) is primarily based on:
- Clinical findings 2
- Imaging studies, such as angiography 3, 4
- Histopathological investigations, including biopsy 2, 3, 4
- Microbiological and genetic investigations to complement the diagnostic work-up 2
Key Diagnostic Features
- Necrotizing inflammation of medium-sized arteries 2, 4
- Multiple small aneurysms involving small and medium-sized arteries, detectable at angiography 3
- Involvement of gastrointestinal and renal arteries is frequent in PAN 3
- Any organ might be affected, except the lungs 4
Diagnostic Considerations
- The diagnosis of PAN should be considered when multiple small-sized aneurysms are present at angiography, even if biopsy is negative 3
- The integration of clinical, angiographic, and biopsy findings is required for diagnosis 4
- Differential considerations for PAN include other forms of vasculitis, such as Churg-Strauss angiitis 5