Peripheral T-cell lymphomas (PTCL) account for about 10% to 15% of all non-Hodgkin lymphomas in the United States. PTCLs are classified into various subtypes. Peripheral T-cell Lymphoma, Not Otherwise Specified (PTCL, NOS) is the most common subtype in North America and Europe where it comprises between 30% and 50% of all PTCLs. It is less common in Asia. It affects older individuals with the median age around 60 years. There is slight male predominance.Most patients present at advanced stages with nodal as well as extranodal involvement (bone marrow, liver, spleen, and skin). The clinical presentation includes generalized lymphadenopathy, sometimes accompanied by fever, eosinophilia, pruritus and weight loss.PTCL, NOS, are aggressive tumors that respond poorly to therapy and frequently relapse. The 5-yr overall survival rate is about 30%.