What are the major organs involved in classic (systemic) polyarteritis nodosa (PAN)?

Kidneys, heart, liver, gastrointestinal (GI) tract, and peripheral nerves. PAN, in its classic form, is a multisystem, segmented necrotizing inflammation of small- and medium-sized muscular arteries. Signs and symptoms are nonspecific and constitutional, reflecting the organ involvement. Pulmonary arteries are typically not involved. The mean age of onset is 48 years, with a male:female ratio of about 4:1. Diagnosis is established by demonstrating vasculitic changes on biopsy of involved organs or by demonstrating typical aneurysms of medium-sized vessels on angiography.

Ishiguro N, Kawashima M: Cutaneous polyarteritis nodosa: a report of 16 cases with clinical and histopathological analysis and a review of the published work, J Dermatol 37:85–93, 2010.