Nasal NK/T Cell Lymphoma: A Study Of Its Neoplastic Cell Lineage And Subsets

Nasal NK/T-cell lymphoma is a peculiar extranodal lymphoma among non-Hodgkin lymphoma. The tumor is typically located in the nasal cavity and therefore the name "nasal NK/T-cell lymphoma" may be used as a synonym for those cases presenting in the nasal region. It has a close relationship with IFNection of EBV and more prevalent in Asia, Mexico, and Central and South America whereas it is rare in Europe and North America. Nasal NK/T-cell lymphoma was named as malignant midline reticulosis, polymorphic reticulosis, lethal midline granuloma, malignant granuloma, necrosis granuloma, angiocentric T-cell lymphoma, T-cell lymphoma of midline, peripheral T-cell lymphoma of midline etc in the past. The neoplasm is characterized by its aggressive clinical features representing nasal cavity and midfacial destroy and the histological features presenting as mass of coagulative necrosis, a heavy admixture of inflammatory cells, polymorphic medium cell show an angiocentric and angiodestructive growth pattern. The lineage of the neoplasm has long been studied during the past years, but Owning to its low incidence of the disease, the research is far below enough. Its neoplastic cell lineage and the name of the tumor have long been controversial.In the present study, most cases appear to be NK-cell neoplasms (EBV+ CD56+) while rare cases show an EBV+ CD56- cytotoxic T-cell phenotype. As a result, it is postulated that the neoplastic cell originated from NK cell (NK) or cytotoxic T-cell (Tc) and it is renamed as nasal NK/T cell lymphoma. Recently, new well-defined disease entities have been described in the WHO lymphoma classification based on tumor cell biology combined withanatomical site, clinical features, Epstein-Barr virus (EBV) status, and cell lineage as determined by immunophenotype and genotype.Cytotoxic T-cell (Tc or CTL), along with NIC-cell make up of the cytotoxic lymphocyte. Parts of Tc were named as NK like T-cell because they can express NFC-cell associated marker (NKT). So the cytotoxic lymphocytes include in fact Tc, NKT and NK. That is to say the nasal NK/T cell lymphoma maybe originated from either of them.Recently immunological research indicates that T cell and NK cell are close related in the growth and differentiation procession, they have common precursor cells. Under different biology medulation mechanism, the precursor NK/T cell differentiated into T or NK cell. Mature T cells exist in four populations, defined by their difference antigen recognized receptor and function. They were CD4+ T helper cell (Thl/Th2) and CD8+ cytotoxic (Tcl/Tc2) subsets. Thl-type CD4 cells primarily secrete cytokines such as IL-2 ,TNF-P and IFN- Y , which mediate cellar immunoreactions whereas Th2 cells secrete cytokines such as IL-4, IL-5, and IL-10, which promote the production of antibody and mediate humoral immunoreactions. Recently, NK cells were also shown to be divisible into NK1 (IFN-r producing) and NK2(IL-5 and IFN-r producing).To conclude, the question about the subsets of the neoplastic cell of the nasal NK/T cell lymphoma still hasn't been answered although it has been described as a new well-defined disease entity in the WHO lymphoma classification. Are lymphomas located in the nasal all originated NK/T cell? Are there any other types of lymphoma? How about the proportion of NK and T-cell originated lymphoma in nasal NK/T cell lymphoma? How about the subsets in NK or T-cell lymphoma? To answer these questions will benefit not only the diagnoses of nasal NK/T cell lymphoma or other types of lymphoma but also the understanding of its peculiar clinical and histopathology character. The research of the subsets about nasal NK/T cell lymphoma has't found reported.To further understand the importance of the standards for nasal NK/T cell lymphoma as a newly defined entity, 41 cases of lymphoma originated from nasal region that diagnosed as midline reticulosis, malignant granuloma,peripheral T-cell lymphoma of midline and nasal NK/T cell lymphoma in the past were studied for their clinicopathol...