Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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August 26, 2021
Polyarteritis Nodosa
- Background:
- Polyarteritis nodosa (PAN) is a transmural necrotizing vasculitis involving small- and medium-sized muscular arteries.
- It is a multisystem disease with common involvement of joints, gastrointestinal system, kidneys, peripheral nerves, and skin.
- The central nervous system can be involved in up to 10% of cases.
- PAN usually spares the lungs.
- The male to female ratio is 1.5:1, with peak age of presentation at 40–60 years.
- Pathologic findings include multiple aneurysms involving medium and small arteries, occlusions, stenosis, and thrombosis.
- Hepatitis B virus and HIV have been implicated in its pathogenesis.
- Clinical Presentation:
- Symptoms vary according to the organ of involvement. Motor and sensory peripheral neuropathy affecting radial, ulnar, and peroneal nerves is very common. CNS manifestations include encephalopathy, focal neurologic deficits, or seizures.
- Pneumomediastinum is a rare complication. It can occur because of leakage of air from ruptured alveoli/airway extending along the bronchovascular structures into the mediastinum. Until now, only 1 case of PAN presenting with pneumomediastinum has been reported in literature to our knowledge.
- Key Diagnostic Features:
- PAN is characterized by the formation of aneurysms due to destruction and weakening of vessel wall. Systemic vessels, most commonly renal (in up to 80% of cases), mesenteric, skeletal muscle, CNS, cardiac, bronchial, and testicular, etc. can be involved due to aneurysms. Aneurysmal subarachnoid hemorrhage or territorial/focal infarcts from vascular occlusion may be seen in the CNS.
- Angiographic imaging features include thrombosis of vessels in the acute stage and stenosis in chronic stages due to intimal proliferation. Vessels show a beading appearance due to alternate segments of stenosis and dilatations. Dissections may also be seen in the form of tapering of the vessel or double lumen.
- Differential Diagnoses:
- Other vasculitis syndromes involving small and medium vessels: Granulomatosis with polyangiitis (Wegener granulomatosis) and eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome); may present with aneurysmal SAH and vascular occlusions, however, such numerous aneurysms are not seen
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Reversible cerebral vasoconstriction syndrome shows multifocal irregularity and narrowing of multiple vessels; however, it presents with thunderclap headache and is reversible within 3 months.
- Infective endocarditis or other bacteremic diseases may present with multiterritorial vascular occlusions, but vascular irregularity is not seen.
- Mycotic intracranial aneurysms occur at cortical branches of the vascular tree and may have associated vascular irregularities; however, there is absence of other systemic manifestations as in PAN.
- Myxomatous aneurysms are seen as multiple fusiform aneurysms in distal vessels. These are formed secondary to myxomatous infiltration of the vessel wall by tumor emboli. A predominantly fusiform appearance and detection of atrial myxoma in systemic work-up differentiate these cases from PAN.
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Treatment:
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Patients with mild disease without hepatitis are managed with glucocorticoids. Additional immunosuppressive agents like azathioprine or methotrexate are used in steroid-resistant or intolerant patients.
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Cyclophosphamide and glucocorticoid combination is given in moderate-to-severe PAN with antiviral therapy for patients with hepatitis.
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Ruptured aneurysms not resolving by medical management can be treated by endovascular coiling.
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Mechanical thrombectomy of an occluded vessel should be avoided as there is high risk of rupture of the vessel and reperfusion failures.
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