Histologic features: (a) diffuse proliferation of lymphoid tumor cells (hematoxylin-eosin stain (HE), magnification ×200) was observed. (b) Large pleomorphic cells with an abundant cytoplasm, sometimes containing prominent nucleoli, were verified. “Hallmark” cells with eccentric, horse-shoe, or kidney-shaped nuclei were also identified (HE, magnification ×400). Immunohistochemical findings: sections showing tumor cells are positive for (c) CD30 with a membrane and Golgi distribution (streptavidin-biotin, ×400 magnification) and (d) Ki-67 (streptavidin-biotin, ×400 magnification).