From the Guidelines
Granulomatosis with polyangiitis (GPA) and polyarteritis nodosa (PAN) are distinct vasculitis disorders with different clinical presentations, histological characteristics, and treatment approaches. The primary difference between GPA and PAN lies in the size of the vessels affected and the presence of granulomatous inflammation. GPA primarily affects small to medium vessels, particularly in the upper and lower respiratory tracts and kidneys, and is characterized by granulomatous inflammation, as noted in the 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of antineutrophil cytoplasmic antibody-associated vasculitis 1. In contrast, PAN affects medium-sized vessels throughout the body, sparing the lungs, and does not involve granuloma formation, as described in the 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of polyarteritis nodosa 1.
Some key differences between GPA and PAN include:
- Vessel size: GPA affects small to medium vessels, while PAN affects medium-sized vessels
- Granulomatous inflammation: GPA is characterized by granulomatous inflammation, while PAN is not
- ANCA association: GPA is associated with anti-neutrophil cytoplasmic antibodies (ANCA), specifically PR3-ANCA in most cases, while PAN is not ANCA-associated
- Clinical manifestations: GPA typically presents with sinusitis, bloody nasal discharge, pulmonary infiltrates, and glomerulonephritis, while PAN commonly manifests with abdominal pain, peripheral neuropathy, skin lesions, and hypertension
Treatment for both conditions involves immunosuppression, typically with corticosteroids and cyclophosphamide for induction, followed by maintenance therapy with less toxic agents like azathioprine or methotrexate, though specific regimens may vary based on disease severity and organ involvement 1. It is essential to note that the treatment approach for GPA and PAN may differ due to their distinct pathophysiological mechanisms and clinical presentations.
From the Research
Differences between Granulomatosis with Polyangitis (GPA) and Polyarteritis Nodosa (PAN)
- GPA is a systemic necrotizing vasculitis that affects small- and medium-sized blood vessels, often associated with cytoplasmic ANCA 2.
- GPA typically involves the upper and/or lower respiratory tract and kidneys, with clinical characteristics such as ear, nose, and throat manifestations, lung nodules, and rapidly progressive necrotizing glomerulonephritis 2.
- In contrast, Polyarteritis Nodosa (PAN) is a systemic vasculitis that primarily affects medium-sized blood vessels, without granulomatosis or ANCA association.
- PAN typically presents with symptoms such as hypertension, renal involvement, and gastrointestinal manifestations, but does not typically involve the respiratory tract or have granulomatous inflammation.
Key Distinctions
- GPA is characterized by granulomatous inflammation and pauci-immune necrotizing glomerulonephritis, whereas PAN is characterized by necrotizing inflammation of medium-sized blood vessels without granulomatosis 3.
- GPA often involves the respiratory tract, whereas PAN does not typically involve the respiratory tract.
- GPA is often associated with ANCA, whereas PAN is not typically associated with ANCA.
Treatment and Prognosis
- GPA treatment typically involves a combination of immunosuppressant drugs and corticosteroids, with a focus on inducing and maintaining remission 2, 4.
- PAN treatment also involves immunosuppressant drugs and corticosteroids, but the specific treatment approach may differ depending on the severity and extent of disease.
- GPA has a relatively high rate of relapse, with 50% of patients experiencing relapse within 5 years 2, whereas PAN has a more variable prognosis depending on the severity and extent of disease.