MYC and leukemia: This is evidenced by findings such as weak or missing CD20, negative smIg and light chain, and TdT expression that varies from absent, scattered, weak, focal, to diffuse.Even under the current WHO classification diagnostic criteria, there are some cases of MYC-rearranged B-cell lymphoma/leukemia with aberrant immature features in which it is difficult to determine whether the disease should be diagnosed as B-ALL/LBL or mature BCL.