PAX5 and neoplasm: The initial IHC revealed that the tumor cells were positive for CD30 and MUM-1, but negative for CD3, CD4, CD5, CD8, CD10, CD19, CD20, CD23, CD38, CD45, CD45RO, CD56, CD79a, CD138, Pax-5, immunoglobulin light chains (κ and λ), epithelial membrane antigen (EMA), anaplastic lymphoma kinase (ALK), Bcl-2, and Bcl-6 (Fig. 4b-g).