Fatal fulminant hypereosinophilic syndrome with a petechial rash in a 16-year-old girl.

Peripheral blood eosinophilia and eosinophilic tissue infiltration characterize the hypereosinophilic syndrome, which if untreated can be fatal. Its manifestations are protean. Often a diagnosis of exclusion, it presents diagnostic challenges. A fatal case of hypereosinophilic syndrome in a 16-year-old girl with petechiae, edema, urticaria, and diffuse erythema unfolded over 2 weeks. The histopathology of the petechiae demonstrated an eosinophilic and mixed cell interstitial and perivascular infiltrate and microthrombi in vessels. There was no evidence of T-cell clonality. Despite treatment with cyclosporine and methylprednisolone, she died. The age group; fulminant, fatal course without neoplasia; striking eosinophilia; and petechial rash are notable.