Fig. 1

Morphology of different subtypes of T-cell and natural killer (NK)-cell lymphoma (hematoxylin–eosin staining, ×400). a Extranodal NK/T cell lymphoma, nasal type (ENKTL) shows medium-sized tumor cells with apoptotic bodies. b Angioimmunoblastic T-cell lymphoma (AITL) shows proliferation of high endothelial venules, polymorphic infiltrating cells, and cells with clear-to-pale cytoplasm. c Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) shows medium- to large-sized polymorphic tumor cells with high mitotic figure rates. d Anaplastic lymphoma kinase (ALK)-positive, anaplastic large-cell lymphoma (ALCL) shows cells with horseshoe or kidney-shaped nuclei and inflammation