Extranodal NK/T-cell lymphoma (ENKTL), nasal type, may be of NK or T-cell origin; however, the proportion of T-ENKTLs and whether they are of αβ or γδ type remains uncertain. To elucidate the cell of origin and detailed phenotype of ENKTL and assess any clinicopathologic associations, 67 cases of ENKTL from Thailand were investigated, together with 5 γδ enteropathy-associated T-cell lymphomas (EATLs) for comparison. In all, 70% of the ENKTL were T-cell receptor (TCR) β,γ and, in cases tested, δ negative (presumptive NK origin); 5% were TCR γδ, 3% were TCR αβ, 1% were TCR αβ/γδ, and 21% were indeterminate. Out of 17 presumptive NK-ENKTLs tested, 3 had clonal TCR rearrangements. All cases were EBV and TIA-1; >85% were positive for CD3, CD2, granzyme B, pSTAT3, and Lsk/MATK; and all were CD16. Presumptive NK-ENKTLs had significantly more frequent CD56 (83% vs. 33%) and CXCL13 (59% vs. 0%) but less frequent PD-1 (0% vs. 40%) compared with T-ENKTLs. Of the NK-ENKTLs, 38% were Oct-2 compared with 0% of T-ENKTLs, and 54% were IRF4/MUM1 compared with 20% of T-ENKTLs. Only αβ T-ENKTLs were CD5. Intestinal ENKTLs were EBV and had significantly more frequent CD30, pSTAT3, and IRF4/MUM1 expression but less frequent CD16 compared with γδ EATL. Significant adverse prognostic indicators included a primary non-upper aerodigestive tract site, high stage, bone marrow involvement, International Prognostic Index ≥2, lack of radiotherapy, Ki67 >40%, and CD25 expression. The upper aerodigestive tract ENKTLs of T-cell origin compared with those of presumptive NK origin showed a trend for better survival. Thus, at least 11% of evaluable ENKTLs are of T-cell origin. Although T-ENKTLs have phenotypic and some possible clinical differences, they share many similarities with ENKTLs that lack TCR expression and are distinct from intestinal γδ EATL.

Background Subcutaneous panniculitis‐like T‐cell lymphoma (SPTL) as strictly defined by World Health Organization‐European Organization for Research and Treatment of Cancer classification is a rare cytotoxic α/β T‐cell lymphoma, characterized by primary involvement of subcutaneous tissue mimicking panniculitis. Objectives To describe the clinicopathologic, immunophenotypic, and molecular features of SPTL. Methods A 10‐year retrospective study of 18 patients diagnosed with SPTL was thoroughly reviewed according to clinicopathology, immunophenotype, and T‐cell receptor (TCR) gene rearrangement. Results Of the 18 patients, 16 patients were definitely diagnosed with SPTL. The median age was 26 years (ranged 14‐53 years) with female predominance. Most patients presented with prolonged fever and subcutaneous nodules and/or plaques, usually located on lower extremities. 37.5% of patients had hemophagocytic syndrome. The main histopathology was lobular panniculitis with rimming of atypical lymphocytes highlighted by CD3+, CD8+, Beta‐F1+, granzyme B+, and Ki‐67 (50%‐90%). Monoclonal TCR gene rearrangement was found in 50% of patients and upper extremities involvement indicated a poor prognosis. Conclusion The correlation between clinicopathologic and immunophenotypic study is the most helpful method to give a precise diagnosis of SPTL. Rimming of CD8+ atypical lymphocytes highlighted by high Ki‐67 index is highly specific for the diagnosis of SPTL.

Systemic reports on the descriptive epidemiology of non-Hodgkin lymphoma (NHL) from Southeast Asia are scarce. A nationwide multi-institutional registry was conducted to compare the histopathology, clinical features, and survival of Thai adult patients with NHL using large registries, especially those from Far East Asia (FEA). Using a web-based registry system, 13 major medical centers from the 4 geographic regions of Thailand prospectively collected, from 2007 to 2014, the diagnostic pathology, according to the World Health Organization classification, 2008, clinical features and survival of 4056 patients who were newly diagnosed with NHL. The median age of the patients was 56 years (range, 16-99 years). The male-to-female ratio was 1.3:1. From the total of 4056 patients, T/NK-cell lymphoma (TNKCL) accounted for 12.6% of cases, and 5.1% had human immunodeficiency virus-associated lymphoma. The four leading histological subtypes were diffuse large B-cell lymphoma, not otherwise specified (58.1%); follicular lymphoma (5.6%); extranodal mucosa-associated lymphoid tissue lymphoma (5.2%); and peripheral T-cell lymphoma, not otherwise specified (4.0%). With a median follow-up duration of 46.1 months, the median overall survival of B-cell NHL was significantly longer than that of patients with TNKCL (76.5 vs 28.8 months, P = .0001). Compared to FEA, the Thai registry had an approximately one-half lower relative frequency of TNKCL; the prevalence of extranodal mucosa-associated lymphoid tissue lymphoma was much lower than in Korea, and the frequency of extranodal TNKCL, nasal type, was strikingly low compared to China. It is concluded that while the median age of Thai patients with NHL was approximately a decade younger than for Caucasians, the long-term survival rates for most histological subtypes were comparable. While the histological distribution generally complied with the characteristic Asian features, some differences from FEA were observed.