ABSTRACT
Nasal natural killer (NK)/T-cell lymphoma is a unique type of mature T/NK-cell lymphoma, that is invariably associated with Epstein–Barr virus, a distinct extranodal homing pattern, and a unique pattern of geographical distribution. The unique racial distribution of nasal NK/T-cell lymphoma suggests a pertinent role for genetic predisposition. Nasal NK/T-cell lymphoma cells usually show Epstein–Barr virus (EBV) latency type II phenotype, and express latent viral proteins, including Epstein–Barr nuclear antigen 1 and latent membrane protein 1. Common histological changes of NK/T-cell lymphoma are polymorphous infiltration of small, medium, and large atypical lymphocytes with accompanying inflammatory cells of varying degree. The histology of NK/T-cell lymphoma is characterized by angioinvasion and necrosis, due to the production of Fas cytokines and cytotoxic granules by the malignant NK cells. A separate prognostic index for mature T-cell lymphoma applied to a limited subset of NK lymphoma, replacing extranodal site and stage with marrow positivity, has had some success.
