Treatment of Extranodal Natural Killer/T-Cell Lymphoma

Extranodal natural killer (NK)/T-cell lymphoma, nasal type, is an aggressive lymphoma marked by extensive necrosis and angioinvasion, most often presenting in extranodal sites, in particular the nasal or paranasal sinus region.[1] Other extranodal sites include the palate, trachea, skin, and gastrointestinal tract. Hemophagocytic syndrome may also occur; historically, these tumors were considered part of lethal midline granuloma.[2] Tumor cells are typically NK cells with immunophenotyping showing CD3 and CD56 expression. In nearly all cases, Epstein-Barr virus (EBV) is detectable in the tumor cells. Aggressive NK cell leukemia (ANKL) is a separate but related diagnosis, which was previously recognized as a subset of large granular lymphocyte (LGL) leukemia, and is characterized by mature NK cell neoplastic involvement of the blood or marrow involvement with a particularly aggressive course and poor prognosis.[3] A benign NK-cell enteropathy (EBV negative) on endoscopic biopsy can be distinguished from NK/T-cell lymphoma.[3] Extranodal NK-cell lymphoma (ENKL), nasal type is rare in Western countries and more commonly seen in Asia, where it represents 3% to 8% of all lymphoma cases. Most cases present with nasal involvement and localized disease. Both extranasal and advanced-stage (stages III–IV) disease are associated with poor prognosis.[4,5]