BCL6 and diffuse large B-cell lymphoma: Immunohistochemistry of intrathoracic biopsy revealed that the tumor cells were positive for CD20, CD30, c-Myc, BCL-2, Mum-1, and PD-L1 but negative for CD3, CD5, CD10, BCL-6, PD-1, and cyclin D1, conforming to the pathological diagnosis of diffuse large B-cell lymphoma (DLBCL) (Figure 2(a))).