Classification, incidence, and overall survival of PTCL subtypes. (A) Classification of peripheral T/NK cell lymphoma. PTCL classification is based on several parameters including clinical presentation, pathological, genetic features, and their association with normal cellular counterparts. Of the >30 PTCL entities recognized as distinct entities either by WHO or International Consensus Classification, the major subtypes present predominantly as nodal, extranodal, disseminated (leukemic), or cutaneous diseases, indicating that disease localization represents relevant diagnostic criteria for major PTCL entities. (B) Frequency of the PTCL entities. Epidemiological findings from published sources are reported (from North America [Bellei et al¹⁷¹ and Hsi et al¹⁷²], the United States [Adams et al¹⁷³ and Ruan et al¹⁷⁴], South America [Fischer et al¹⁷⁵], Africa [Fitzpatrick et al¹⁷⁶ and Belarbi et al¹⁷⁷], Western Europe [Laurent et al⁷], Central Europe [Janikova et al¹⁷⁸], Nordic [Ellin et al⁸], India [Park et al¹⁷⁹ and Nemani et al¹⁸⁰], China [Park et al¹⁷⁹ and Liu et al¹⁸¹], and Asia [Park et al¹⁷⁹ and Yoon et al¹⁸²]) (see citations in supplementary Table 2). The average frequencies from these studies were estimated and presented as pie charts for each specified region as indicated. ALK⁺ALCL vs ALK^–ALCL cases were compared when data were reported. It must be noted that the frequencies presented may not represent the full spectrum of PTCL subtypes due to variations in data reporting across countries and also lack of requisite immunostains for current classification due to limited resources. Because of the exclusion of “other T-NHLs in individual regions or countries,” pie graphs may overrepresent the frequency of some PTCL subtypes. Different countries may have different reporting standards, subtype classifications, methodologies, or levels of data accuracy, which can affect the comprehensiveness and comparability of the data. However, for the worldwide frequency pie graph, the “other T-NHLs” were included to reflect the actual frequency of PTCL subtypes (see supplemental Table 2). (C) Overall survival of histological PTCL subtypes. These patients were generally treated with an anthracycline-containing regimen (adapted from Vose et al¹). Regional 5-year survival is displayed in North America (Hsi et al¹⁷²), Czech (Janikova et al¹⁷⁸), and Asia (Yoon et al¹⁸²). AITL, angioimmunoblastic T-cell lymphoma; CTCL, cutaneous T-cell lymphoma; EATL, enteropathy-associated T-cell lymphoma; HSTL, hepatosplenic T-cell lymphoma; MEITL, monomorphic epitheliotropic intestinal T-cell lymphoma; T-NHL, T-cell non-Hodgkin lymphoma.