Bone marrow fibrosis as prognostic marker in adult patients with acute lymphoblastic leukemia

The role of bone marrow (BM) fibrosis on outcomes of children with acute lymphoblastic leukemia (ALL) has been described with inconsistent results. In adults, there is no information regarding its significance. The aim of this study was to describe the prognostic impact of BM fibrosis in this group of patients. We included 88 biopsies of 44 adult patients. Reticulin and Masson trichrome stains were performed. Fibrosis was graded by modified Bauermeister scale and volume of reticulin/collagen fibers, both methods had good correlation. Survival analyses were performed regarding (1) the presence or not of significant fibrosis at diagnosis, (2) the reduction or not of fibrosis post-treatment, and (3) the amount of fibrosis at diagnosis combined with the depth of the reduction post-treatment. Sixty-six percent of the patients had significant fibrosis at diagnosis (Bauermeister ≥ grade 2) and 45% achieved a significant reduction (≥ 50% volume of reticulin/collagen fibers) post-treatment. The presence of fibrosis at diagnosis had no clear impact on outcomes; however, a significant reduction of the fibrosis post-treatment in patients with standard-risk ALL was correlated with longer RFS (19.1 months vs 10.6 months, p = .022) and OS (54.4 months vs 16.4 months, p = .033). Patients who had fibrosis at diagnosis combined with a deep reduction post-treatment had a better RFS and OS compared with those who did not have fibrosis at diagnosis regardless of its reduction or those who did not achieve a deep reduction. To our knowledge, this is the first study to describe an impact of BM fibrosis reduction post-treatment in adult patients with ALL.