Superficial venous thrombophlebitis as the initial manifestation of hypereosinophilic syndrome: study of the first 3 cases.

BACKGROUND Superficial venous thrombophlebitis (SVT), often perceived as benign, can coexist with hypercoagulable states. Predisposing risk factors for SVT are similar to those observed for deep venous thrombosis. Association of eosinophilia with SVT is a rare situation that can reveal neoplasia, malignant blood disorders, or vasculitis, but it has never been described in hypereosinophilic syndrome (HES). We herein describe the clinical and biological features, outcome, and response to therapy of 3 patients with SVT associated with eosinophilia that revealed HES. OBSERVATIONS Superficial venous thrombophlebitis was the initial manifestation of HES in all 3 patients. The mean eosinophil count at diagnosis was 2.4 x 10(3)/muL. All patients received corticosteroids and anticoagulants as the initial treatment, with marked improvement of SVT and return of the eosinophil count to reference limits. All patients experienced relapse and remained dependent on corticosteroid therapy. Two patients received interferon alfa with dramatic regression of SVT, allowing a decrease in the dose of corticosteroids. CONCLUSIONS We report, to our knowledge, the first 3 cases of SVT related to HES. Superficial venous thrombophlebitis was difficult to treat, with dependence on corticosteroid therapy and partial efficacy of anticoagulant and antiplatelet therapy. Interferon alfa was effective in preventing relapse of SVT related to HES. Mechanisms implied in this thrombogenesis are multiple and remain speculative.