Relevance and dynamics of myelofibrosis regarding hematopoietic reconstitution after allogeneic bone marrow transplantation in chronic myelogenous leukemia - a single center experience on 160 patients

A retrospective single center study was performed on 516 trephine biopsies derived from 160 patients with stable phase Ph+-CML and allogeneic BMT, Fol lowing morphometric quantification of reticulin-collagen fibers we tried to elucidate (1) the dynamics of bone marrow fibrosis in the post-transplant period; and (2) the influence of manifest myelofibrosis on relevant engraft ment parameters. An evaluation of fiber density at standardized endpoints a fter BMT was carried out on a selected cohort of 124 patients (399 biopsy s pecimens), A manifest myelofibrosis (more than a three-fold increase compar ed to the normal fiber content) before BMT was found in 26% of our patients . Concentrating on bone marrow areas with reconstituting hematopoiesis, sev eral findings emerged. Pretransplant myelofibrosis was associated,vith an i nitial regression following BMT, but insidiously recurred in the areas of r egenerating hematopoiesis or developed in a few patients without increased pregraft fibers during the post-transplant period (mean observation time mo re than 4 months), Severe acute GVHD (grades III and IV) was significantly correlated with a greater amount of reticulin fibers in the early post-tran splant period (9 to 30 days after BMT), Regarding engraftment parameters, a significant delay was detectable in the time to achieve transfusion indepe ndence for the patients with manifest myelofibrosis compared to those witho ut pretransplant fiber increase.