MKI67 and mantle cell lymphoma: The proliferation rate, expressed as Ki-67 expression, and blastoid morphology have also proved reliable in the identification of a high-risk biology subgroup with significantly shorter survival and worse response to intensive chemotherapy regimens, with the particular relevance of the deletion of the short arm of chromosome 17 (del(17p)) or TP53 mutations, which have independent prognostic value in MCL patients [10]; this has been translated into the new lymphoma classification systems, whereby investigating the Ki67 proliferation index and TP53 status is mandatory at MCL diagnosis [6].