Representative bone marrow histology in myelofibrosis with myeloid metaplasia (MMM) both at times of initial diagnosis and during leukemic transformation (LT). (A) Representative patient at time of diagnosis of MMM (B) Patient from panel A at time of LT. (C) Patient from panel A after induction chemotherapy reverting to chronic-phase MMM. (D) Focal transformation (top right-hand corner) in a background of typical MMM-related histologic changes (E) Megakaryocytes at time of diagnosis of MMM (large and clustered) compared with the smaller megakaryocytes seen in LT (B). (F) Focal residual leukemia (bottom right-hand corner) in background of regeneration in a patient treated with induction chemotherapy. Images were acquired with a Leitz Wetzler Orthoplan microscope (Leitz, Wetzler, Germany), with a 40×/0.75 NA objective, using an Orthocam camera, and processed with Adobe Photoshop 7.0 (San Jose, CA). Cells were stained with hematoxylin and eosin.