MMP9 and T-cell non-Hodgkin lymphoma: In the current study, we performed an immunohistochemical study of the expression of P-glycoprotein and MMP-9 in nasal NK/T-cell lymphoma and other types of nasal lymphomas (non-NK/T cell lymphoma) to elucidate the unique characteristics of nasal NK/T-cell lymphoma, such as its resistance of chemotherapy and strong metastatic tendency.