Figure 1

Bone marrow core biopsy at the time of initial FIP1L1- PDGFRA rearrangement discovery. The bone marrow is hypercellular (100%), with prominent eosinophilia and myeloid hyperplasia, mild increase in immature cells, and features of myelofibrosis manifesting primarily as cellular streaming. (a: 10× objective; b: 20× objective; hematoxylin and eosin stain).