Chronic eosinophilic leukemia-not otherwise specified has a poor prognosis with unresponsiveness to conventional treatment and high risk of acute transformation

Abstract

Chronic eosinophilic leukemia-not otherwise specified (CEL-NOS) is a rare disorder with hypereosinophilia and an increased number of blood or marrow blast (<20%) or an evidence of eosinophil clonality. We evaluated the clinical outcome of 10 patients with CEL-NOS. Seven males and three females at a median age of 62 years (range, 23-73) were included. The median leukocyte count at diagnosis was 33.4 × 10 9/l (range, 9.3-175.0) with a median eosinophil count of 15.6 × 10 9/l (range, 1.5-136.0). Median hemoglobin and platelets were 11.0 g/dl (range, 8.3-13.3) and 158 × 10 9/l (range, 31.0-891.0), respectively. Clinical manifestations included splenomegaly (n = 7), hepatomegaly (n = 6), cardiac failure (n = 2), and lung infiltrations (n = 1). Median survival from diagnosis to death for entire cohort was 22.2 months (range, 2.2-186.2). Five of the 10 studied patients developed acute transformation (AT) after median of 20 months from diagnosis (range, 1.6-41.9). None of patients with AT is alive at the time of last follow-up. Median time from AT to death was 2 months (range, 1.0-6.1). Among five patients who did not develop AT, three died in active disease. Two patients are alive in complete remission; first underwent allogeneic stem-cell transplantation preceding by intensive induction chemotherapy; the second remains on imatinib with hydroxyurea. Except the latter patient, imatinib was ineffective in our study population. CEL-NOS is a rare and aggressive disease with high rate of AT and resistance to conventional treatment. © 2012 Wiley Periodicals, Inc.