Malignancies derived from mature (postthymic) T and NK cells, collectively referred to as peripheral T-cell lymphomas (PTCL), encompass a variety of heterogenous, uncommon, and rare diseases, altogether accounting for between 10% and 15% of all non-Hodgkin's lymphoma in the Western hemisphere. It is noteworthy that there is an overall higher frequency of PTCL in Asia estimated at approximately 24% and in Central/South America than in Western countries, especially those types associated with viruses, such as human T-cell lymphotropic virus-1 (HTLV-1), implicated in the pathogenesis of adult T-cell leukemia/lymphoma, and Epstein-Barr virus, associated with NK/T-cell lymphoma. 1Of the many subtypes of PTCL, the most common is PTCL not otherwise specified, followed by angioimmunoblastic T-cell lymphoma and systemic anaplastic large cell lymphoma (sALCL). In the current World Health Organization 2008 classification of PTCL, most of the aggressive PTCL are currently included within the nodal, extranodal, and leukemic groups and are generally associated with a relatively poor prognosis compared with B-cell lymphomas as a whole. Although the different subtypes of PTCL vary with respect to clinical features, prognosis, and treatment response, the 2-year failure-free survival for patients with high-risk or intermediate high-risk disease is estimated at only 10%.
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