Mast cell leukemia with t(8;21) and t(12;13): can we classify it as acute mast cell leukemia?

Abstract

We report the case of a 69-year-old man who presented acute leukemia with circulating blasts and numerous atypical mast cells in peripheral blood. Both blasts and mast cells presented identical cytochemistry (myeloperoxidase-negative, tartrate-resistant acid phosphatase-negative, esterase-negative; toluidine blue-positive; and acid phosphatase-positive). Flow cytometry showed a blast population MPO − , DR − , CD34 − , CD117 ++ , CD25 + , and CD2 − . Bone marrow histology revealed infiltration by CD25 + , c-Kit + , and tryptase + cells. Cytogenetics revealed 46,XY,t(8; 21)(q22; q22),der(12),t(12; 13)(p13; q12-14),del(13)(q14) [20]. The KIT D816V mutation was negative. Serum tryptase was very high. He received treatment with tyrosine kinase inhibitors and hydroxycarbamide without any response, and he died of respiratory distress with the finding at necropsy of pulmonary infiltration by mast cells. We highlight the rarity of the case that, in our opinion, could be classified as "acute" mast cell leukemia instead of systemic mastocytosis with an associated hematological neoplasia (WHO).