A rare cause of splenic infarct and fleeting pulmonary infiltrates: polyarteritis nodosa.

A rare multi-system disease with an incidence of about 5/million per year, polyarteritis nodosa (PAN) occasionally may cause splenic vasculitis, usually at arteriole bifurcations, leading to multiple systemic infarcts with extensive confluent systemic necrosis. PAN may also be a cause of fleeting patchy pulmonary infiltrates or pulmonary nodular lesions. The diagnosis is usually difficult and delayed because the clinical manifestations are varied and depend on the site and the extent of the arterial involvement.