“…In all of these diseases, the bone marrow fibrosis is polyclonal in origin, suggesting that it is a reactive process stimulated by activity of an abnormal stem cell clone, e.g., PDGF production. 2,20,40,[42][43][44][45] With effective therapy, fibrosis may be reversible (e.g., interferon-␣ [IFN-␣] in hairy cell leukemia [HCL], IFN-␣ IFN/Gleevec in CML).…”