Resistance to activated protein C: arterial thrombosis associated with autoimmune features.

A 27 year old woman presented with recurrent cerebrovascular strokes in the setting of an ill defined auto-immune disease responsive to corticosteroid therapy. Investigation for a hypercoagulable state revealed activated protein C resistance in the absence of protein C, protein S, or antithrombin III deficiency or anticardiolipin antibodies. Her parents and sibling did not demonstrate APC resistance. This case suggests that activated protein C resistance may be associated with arterial as well as venous thrombotic events and implies that resistance to activated protein C should also be considered in the evaluation of young adults with strokes.