Donor cell-derived myelofibrosis relapse after allogeneic stem cell transplantation

Primary myelofibrosis (PMF) is a rare myeloproliferative\r\nneoplasm characterized by clonal proliferation of mature\r\nmyeloid lineages derived from stem cells (erythrocytes,\r\nleukocytes and magakaryocytes) with variable megakaryocyte atypia associated with reticulin and / or collagen\r\nbone marrow (BM) fibrosis, osteosclerosis, ineffective erythropoiesis, angiogenesis, extramedullary hematopoiesis\r\nand abnormal expression of cytokines.\r\nAllogeneic hemopoietic stem cell transplantation (alloHSCT) is currently the only curative approach for patients with myelofibrosis, and for this reason the number\r\nof allografts for these indications have been growing over\r\nthe past years.\r\nUnfortunately relapse of myelofibrosis (MF) after an alloHSCT occurs in 10-40% of cases: patients usually present with a declining donor chimerism, and a reappearance\r\nof driver mutations if present; BM biopsy is usually consistent with typical megakaryocyte abnormalities and\r\nstromal fibrosis. Ultimately BM cells exhibit progressive\r\nloss of donor chimerism, and the relapse is therefore of\r\nrecipient origin. Here we report two allografted MF patients who relapsed in donor cells