MPO and mixed phenotype acute leukemia: Immunohistochemistry of the excised lymph node revealed that the neoplastic cells expressed CD34, c-KIT (CD117), CD3, CD4, CD5, CD7, myeloperoxidase (MPO, partial), and lysozyme. TdT was only expressed on rare cells, supporting a diagnosis of extramedullary involvement by T/Myeloid MPAL (Figure 2 and Table 1).