Unusual presentation of polyarteritis nodosa.

We describe an unusual presentation of a localized form of polyarteritis nodosa (PAN) manifested by acute onset of severe calf pain. Biopsies of the gastrocnemius muscle and fascia revealed an acute necrotizing arteritis with fasciitis. The lumens of affected vessels were occluded by thrombi. PAN localized to calf muscles is extremely rare. To our knowledge this is the first report of evidence of fascial involvement believed to contribute to the severity of the clinical features of PAN. The occurrence of multiple intraluminal thrombi in conjunction with anticardiolipin antibodies suggested the possibility of a coexisting coagulopathy, and they were also likely contributors to the severity of the pain.