Figure 2. Peripheral blood smear and bone marrow biopsy and aspirate in the present case. (A) Peripheral blood smear showing eosinophilia. (B) Hematoxylin and eosin-stained bone marrow biopsy with hypercellularity with myeloid predominance and eosinophilia (original magnification 100×). (C) Flow cytometry analysis of the bone marrow aspirate. Eosinophils are highlighted in red and account for approximately 14% of analyzed cells. The population of eosinophils demonstrate high side-scatter (corresponding to cytoplasmic complexity and granularity which is high in eosinophils) with bright expression of CD45 (common leukocyte antigen), CD34 (maturity marker that is negative in mature eosinophils), CD11b (positive in eosinophils), CD15 (positive in eosinophils and other mature myeloid cell), and dim CD33 (positive in eosinophils and neutrophils while monocytes are bright positive), and lack expression of HLA-DR (negative in eosinophils and positive in monocytes), CD10 (negative in eosinophils and positive in neutrophils), CD16 (negative in eosinophils and positive in neutrophils), and CD64 (negative in eosinophils, while monocytes are bright positive).