MPO and B-cell non-Hodgkin lymphoma: This mechanism has been partially confirmed in t(8;21)-positive AML (21, 22).Notably, the supplementary immunohistochemical results of the intracranial lesion in this case showed CD20 negativity and MPO positivity, which provided crucial evidence for ultimately ruling out B-cell lymphoma and confirming the diagnosis of myeloid sarcoma (2).