CML patients treated with imatinib have increased iliac crest TBV and altered bone marrow cellularity. Sections of posterior superior iliac spine bone trephines taken at diagnosis were analyzed by histomorphometry and compared with trephines obtained from the same patients after imatinib or α-interferon therapy. (A) Changes in TBV before and after imatinib (■) or α-interferon (•) therapy are shown as lines for individual patients. Bone marrow cellularity of patients at diagnosis of CML (patient 1 [panel B] and patient 2 [panel D]) and after 42 months (patient 1 [panel C]) and 33 months (patient 2 [panel E]) of imatinib therapy is shown. T indicates trabecular bone; N, normal marrow; and L, leukemic cells. Original magnification 40× for panels B-E. Micrographs were acquired with a CKX41 inverted microscope (Olympus, Center Valley, PA) and images captured using DPII image capture system (Olympus).