Fig. 1

Pathological findings of mantle cell lymphoma. a Neoplastic cells involving the small intestine (hematoxylin and eosin counterstain, original magnification ×100). The cell proliferation can be nodular or diffuse, with a mixed nodular pattern. b The CD20 antigen was positive in neoplastic cells (immunoperoxidase with hematoxylin counterstain, original magnification ×40). Tumor cells are small- to medium-sized and are composed of a dense, monotonous infiltration of small to intermediate cleaved cells with small, irregularly shaped nuclei and scanty cytoplasm. c The CD79a antigen was positive in neoplastic cells (immunoperoxidase with hematoxylin counterstain, original magnification ×200). d The CD20 antigen was positive in neoplastic cells (immunoperoxidase with hematoxylin counterstain, original magnification ×400)