The 2017 WHO Classifcation lists approximately 30 disease entities under the category of mature T-cell and natural killer (NK) cell neoplasms. These are rare forms of lymphoma that account for 7% (slightly below 10% in Japan) of all lymphomas. A global retrospective observational study on peripheral T-cell lymphoma (PTCL) conducted by the International T-cell Lymphoma Project found that the most prevalent entities in Western countries were PTCL not otherwise specifed (PTCL-NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK-positive anaplastic large cell lymphoma (ALCL), and ALK-negative ALCL. This chapter covers these four entities. Two other PTCL entities common in Japan, adult T-cell leukemia-lymphoma (ATL) and extranodal NK/T-cell lymphoma, nasal type (ENKL), will be covered in another chapter of these guidelines. Cutaneous T-cell lymphoma will not be covered in this chapter because it has its own set of guidelines.

《2017年WHO分类标准》在成熟T细胞和自然杀伤（NK）细胞肿瘤类别下列入了约30种疾病实体。这些罕见淋巴瘤占所有淋巴瘤的7%（日本略低于10%）。国际T细胞淋巴瘤项目组开展的全球回顾性观察研究显示，西方国家最常见的外周T细胞淋巴瘤（PTCL）亚型包括：非特指型PTCL（PTCL-NOS）、血管免疫母细胞性T细胞淋巴瘤（AITL）、ALK阳性间变性大细胞淋巴瘤（ALCL）以及ALK阴性ALCL。本章将涵盖上述四种亚型。在日本高发的另两种PTCL亚型——成人T细胞白血病淋巴瘤（ATL）和鼻型结外NK/T细胞淋巴瘤（ENKL）将在本指南其他章节详述。皮肤T细胞淋巴瘤因已有独立指南，本章不予讨论。