Bone marrow findings post allogeneic transplant for myeloproliferative neoplasms and chronic myelomonocytic leukemia with increased fibrosis

Background: Allogeneic hematopoietic stem cell transplant for myeloid neoplasms with increased fibrosis is uncommon; morphologic features posttransplant can be concerning for persistent disease. Methods: In this retrospective study, we identified 22 patients transplanted for myeloproliferative neoplasms or chronic myelomonocytic leukemia with fibrosis at our institution, and reviewed slides from pretransplant and posttransplant bone marrow biopsies. Clinical features and results of molecular, chimerism, and cytogenetic studies were retrieved from the medical record. Results: Pretransplant bone marrow biopsies commonly exhibited hypercellularity, atypical megakaryocytes, and reticulin fibrosis. At day 100, 36% of biopsies had reticulin grade >MF1 and 33% of those tested had positive molecular studies, with no significant associations between day 100 marrow characteristics and molecular profile or peripheral count recovery times. In the 1 year posttransplant biopsies (n = 12), 7 of 9 had negative molecular studies; of these, none had reticulin grade >MF1, 1 had trichrome 1+, 2 had atypical megakaryocytes, and 1 was hypercellular. Conclusions: Supporting recent literature, our study indicates that persistent day 100 reticulin fibrosis/collagen deposition does not show an association with day 100 molecular status. Our study additionally provides data for 12 patients with 1 year posttransplant marrow biopsies, with the majority of those lacking either increased fibrosis or molecular evidence of persistent disease.