DEVELOPMENT OF SYSTEMIC MASTOCYTOSIS AFTER BONE MARROW TRANSPLANTATION FOR AN ACUTE MYELOID LEUKEMIA: DONOR DERIVEN DISEASE OR SYSTEMIC MASTOCYTOSIS WITH AN ASSOCIATED MYELOID NEOPLASM

Abstract Introduction/Objective Systemic mastocytosis may have variable presentation ranging from an indolent disease to an aggressive form. Systemic mastocytosis with an associated myeloid neoplasm can occur simultaneously, or within an interval of a myeloid neoplasm and should meet the diagnostic criteria of both entities. Methods/Case Report Herein, we present a patient with history of acute myeloid leukemia with KMT2A(11q23) amplification who initially underwent an allogeneic hematopoietic stem cell transplantation from a matched sibling donor. One year later, the patient developed isolated central nervous system relapse, as well as evidence of molecular relapse in the bone marrow and underwent a second allogeneic transplantation, but this time, from a matched unrelated donor. The 100 days post second transplant bone marrow biopsy was negative for involvement by acute myeloid leukemia and the chimerism study revealed evidence of total engraftment with 100% donor cells. Additionally, Fluorescence in situ hybridization analysis detected no evidence of KMT2A amplification. However, morphologic examination of the bone marrow biopsy demonstrated involvement by systemic mastocytosis with multiple dense aggregates of CD117 and tryptase positive mast cells showing spindled cell morphology. Mast cells were positive for CD25 and demonstrated negative expression of CD2 and CD30. PCR analysis of the peripheral blood did not detect evidence of KIT mutation, but serum tryptase was elevated. Results (if a Case Study enter NA) NA Conclusion This case highlights a rare instance of systemic mastocytosis in the setting of remission from an acute myeloid leukemia in a post transplantation bone marrow and represents a diagnostic challenge. While development of systemic mastocytosis in a patient with prior history of an acute myeloid leukemia suggests the possibility of systemic mastocytosis with an associated myeloid neoplasm, some other features including the complete remission and total engraftment of the post transplantation bone marrow with 100% donor cells, raise the possibility of a donor driven disease.