Diagnostic and Therapeutic Approach for Polyarteritis Nodosa (PAN)

Initial Assessment and Diagnosis

The American College of Rheumatology recommends immediately assessing for organ-threatening manifestations to determine disease severity in adults with suspected PAN presenting with constitutional symptoms and hypertension, as this dictates the diagnostic and therapeutic pathway 1, 2
Abdominal vascular imaging (CT angiography or MR angiography) should be obtained for all patients with suspected PAN to establish diagnosis and determine disease extent, identifying characteristic findings including arterial stenoses and occlusions 1, 2
For patients with severe PAN and abdominal involvement who achieve clinical remission, follow-up abdominal vascular imaging should be performed to assess disease control and treatment response 1, 2

Severe PAN should be classified based on the presence of life-threatening or organ-threatening manifestations, abdominal involvement with mesenteric ischemia, central nervous system involvement, or renal insufficiency 2, 3, 4
The American College of Rheumatology recommends initiating treatment with IV pulse glucocorticoids combined with cyclophosphamide for severe PAN, rather than high-dose oral glucocorticoids or glucocorticoids alone 1, 2
For nonsevere PAN, treatment with non-glucocorticoid immunosuppressive agents (azathioprine or methotrexate) combined with moderate-dose oral glucocorticoids is recommended, rather than glucocorticoids alone 2, 3

A deep-skin biopsy (reaching medium-sized vessels of the dermis) should be obtained for suspected cutaneous PAN, rather than a superficial punch biopsy 1, 2, 5
A combined nerve and muscle biopsy should be obtained for suspected PAN with peripheral neuropathy, rather than a nerve biopsy alone 1, 2
Electromyography/nerve conduction studies should be performed initially to confirm peripheral neuropathy and characterize the pattern, and serial neurologic examinations should be used to monitor disease activity in patients with established peripheral motor neuropathy 1, 2, 4

Non-glucocorticoid immunosuppressive therapy should be discontinued after 18 months of sustained remission, rather than continuing indefinitely 2, 3, 4
Glucocorticoid taper duration should be guided by clinical condition, and patients should be monitored with serial clinical examinations assessing skin lesions, neurologic function, blood pressure, and systemic symptoms 2, 3, 4