Figure 1: Main features of our patient. (a) Shows the results of a complete c-KIT sequencing: absence c-KIT mutation, especially in exon 17. Indeed, the patient harbored no c-KIT mutation on any exon. (b) shows the results of bone marrow biopsy. (b1): Coloration HES, 400; (b2) c-KIT immunostaining, 400. Bone marrow aspirates showed in (c1) a mixture of normal mast cell, leukemic round mast cells, and two very atypical nucleated mast cells with loose chromatin, representing more than 30% of nucleated marrow cell. (c2): cluster of atypical mast cells with a round basophilic mass in the cytoplasm. (d): Immunophenotypic profile of mast-cells characterized by strong KIT/CD117 CD2 and CD25 negative.