[Rapidly progressive, refractory eosinophilia with a 250,000/microliter eosinophil count].

: A 31-year-old man had received corticosteroids for 20 months for treatment of a brain tumor, and his blood eosinophil count ranged from 100/microliter to 1,000/microliter. On June 24th, 1998, he was re-admitted because of dyspnea secondary to left massive pleural effusion. Peripheral blood examination revealed an eosinophil count of 48,000/microliter. The eosinophils were hypersegmented, with abnormal distribution of eosinophilic granules and formation of cytoplasmic vacuoles. Blasts and basophils were not increased, hemoglobin was 13.4 g/dl, and the platelet count was 79,000/microliter. Bone marrow was slightly hypercellular with 55% eosinophils and 0.2% blasts. The patient's karyotype was normal, and Wilms' tumor gene was not detected. Serum IgE was normal and serum vitamin B12 and soluble IL-2 receptor were elevated. Serum levels of eosinophilopoietic cytokines, IL-3, IL-5, and GM-CSF, were low. Specimens of pleural fluid contained many eosinophils. Because the eosinophil count increased to 110,000/microliter on July 2nd, hydroxyurea was started without effect. On July 16th, the eosinophil count reached 167,000/microliter, and vincristine was added. The eosinophil count rose to 253,000/microliter the next day, and cytarabine and daunorubicin were administered, but the patient died of septic shock. Although the clinical course suggested eosinophilic leukemia, monoclonal proliferation of eosinophils was not demonstrated. To our knowledge, this is the highest peripheral blood eosinophil count reported in the literature to date.