MKI67 and B-cell non-Hodgkin lymphoma: Pathologic review of the biopsy material revealed two unusual cases of MYC-R B-cell lymphoma: a case of a 6-year-old boy with BL-like morphology, isolated MYC::IGH rearrangement, CD10 positivity and a high Ki67 proliferative index (> 95%) showed TdT positivity.