Hypereosinophilic syndrome as a cause of fatal thrombosis: two case reports with histological study.

Herein we present two cases of hypereosinophilic syndrome with a unique clinical presentation. One patient showed severe systemic thrombosis with splenic rupture and the other patient showed finger gangrene with various systemic symptoms. Both patients were examined histologically, and several characteristics were noted. First, fresh or organized thrombosis with marked eosinophilic infiltration was observed in the cavity and walls of the thrombosed vessels. Second, many eosinophils showed degranulation and were positive for eosinophilic cationic protein on immunohistological examination. Third, the structures of thrombosed vessels were well preserved, which is not observed in systemic vasculitis. These patients exhibited no neoplastic features and were treated with prednisolone with excellent therapeutic results.