MML is an extremely rare form of mast cell differentiation occurring in an advanced myeloid neoplasm, characterized by >10%–19% immature mast cells/ metachromatic blasts in the bone marrow and >5% myeloblasts in the bone marrow and/or peripheral blood; MML demonstrates wild‐type KIT and CD25 negativity, which distinguishes it from MCL. This evidence concerns the gene KIT and mantle cell lymphoma.