Complete and long-lasting cytologic and molecular remission of FIP1L1-PDGFRA-positive acute eosinophil myeloid leukaemia, treated with low-dose imatinib monotherapy.

Myeloproliferative neoplasms associated with FIP1L1-PDGFR rearrangements represent a rare subset of myeloid and lymphoid malignancies, characterised by the presence of eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1 genes. The fusion product of such genes is a tyrosine kinase oncoprotein sensitive to imatinib, which to date results to be the standard of care for FIP1L1-PDGFRA-positive chronic myeloproliferative disorders with eosinophilia. However, the coexistence of FIP1L1-PDGFRA rearrangement associated with acute myeloid leukaemia is extremely rare. Here, we report a rare case of FIP1L1-PDGFRA-positive acute myeloid leukaemia, with marked peripheral blood and bone marrow eosinophilia, treated with low dose of imatinib monotherapy, achieving a rapid and long-lasting complete cytologic and molecular remission, without need for intensive chemotherapy.