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Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of lymphomas derived from a mature T cell (Fig. 9-1). Currently, the World Health Organization (WHO) classification combines mature T- and natural killer (NK)-cell neoplasms under the umbrella term PTCL, and the category is composed of 23 different entities (Table 9-1), based on the different morphologic, phenotypic, molecular, and clinical features, including disease site (1). Most PTCLs lack distinct genetic or biologic alterations that are seen in B-cell lymphomas, such as t(14;18) in follicular lymphoma and t(11;14) in mantle cell lymphoma. Compared with B-cell lymphomas, many types of PTCL develop not in lymph nodes, but in specific extranodal sites such as extranodal NK/T-cell lymphoma, nasal type (ENKL) in the nasal cavity, enteropathy-associated T-cell lymphoma (EATL) in the small intestine, and hepatosplenic T-cell lymphoma (HSTL) in the liver and spleen.


Peripheral T-cell lymphoma: T-cell maturation and organ of involvement. AITL, angioimmunoblastic T-cell lymphoma; ALCL, anaplastic large T-cell lymphoma; ATLL, adult T-cell lymphoma/leukemia; EATL, enteropathy associated T-cell lymphoma; ENKTCL, extranodal NK/T-cell lymphoma; HSTCL, hepatosplenic T-cell lymphoma; NK, natural killer; PTCL, peripheral T-cell lymphoma; PTCL-NOS, PTCL, not otherwise specified; T-ALL, T-cell acute lymphoblastic leukemia; TCL, T-cell lymphoma; T-LBL, T-cell lymphoblastic lymphoma; T-LGL, T-cell large granular lymphocytic leukemia; T-PLL, T-cell prolymphocytic leukemia.

Table 9-1Peripheral T-Cell Lymphomas in World Health Organization Classification, 4th Edition


Peripheral T-cell lymphoma represents 5% to 10% of all lymphomas in the United States (2). The most common histologic subtype is PTCL, not otherwise specified (PTCL-NOS), followed by angioimmunoblastic T-cell lymphoma (AITL) or anaplastic large-cell lymphoma (ALCL), either ALK positive or ALK negative. The three types account for about 60% of all cases of PTCLs (3). The age-adjusted incidence in the United States for PTCL-NOS, AITL, and ALCL is 0.30, 0.05, and 0.25 per 100,000 person-years, respectively (2). Previous studies have indicated that some Asian countries have a higher incidence of PTCL (3). However, age-adjusted incidence estimated by population-based ...

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