Philadelphia chromosome positive (Ph+) describes a leukemia that carries a specific chromosomal translocation. The Philadelphia chromosome results from a translocation of genetic material between chromosomes 9 and 22. From this new genetic configuration arises a so-called fusion gene, which can alter certain pathways that contribute to tumor growth and proliferation. This translocation is present in chronic myeloid leukemia (CML) and some patients with acute lymphoblastic leukemia (ALL). The optimal management of patients with Ph+ leukemia includes the use of a tyrosine kinase inhibitor (TKI) that targets this translocation.