Hypereosinophilic syndrome associated with polycythemia vera.

A 60-year-old woman presented with relapse of polycythemia vera associated with hypereosinophilic syndrome (HES) with abnormal immunologic measures, including increased serum IgE and IgG levels, high levels of circulating immune complexes, rheumatoid factor, and antinuclear antibodies. Treatment with hydroxyurea was followed by a dramatic response of both the polycythemia vera and the HES, with return to normal of the abnormal immunologic measures. This case report documents that evidence of immunologic and myeloproliferative causes of HES may coexist in the same patient.