Extranodal NK/T-cell lymphoma, nasal type, includes cases of natural killer cell and αβ, γδ, and αβ/γδ T-cell origin: a comprehensive clinicopathologic and phenotypic study

Extranodal NK/T-Cell Lymphoma Predominantly Composed of Anaplastic Cells: A Frequently Misdiagnosed and Highly Aggressive Variant

Extranodal NK/T-cell lymphoma (ENKTL) is a non-Hodgkin lymphoma associated with the Epstein-Barr virus that primarily affects individuals in East Asia and indigenous populations in Central and South America. Morphologically, ENKTL typically consists of medium-sized cells or a combination of small and large cells. This report presents 10 cases characterized by predominantly anaplastic cells with diffuse expression of CD30, resembling anaplastic lymphoma kinase-negative anaplastic large cell lymphoma (ALK-negative ALCL) and demonstrating highly aggressive behavior. The cohort included 9 males and 1 female, ranging in age from 29 to 65 years (median age: 47 y). Eight patients presented with nasal disease, while 2 had non-nasal disease. Five patients had stage I/II disease, and the remaining 5 had stage III/IV disease. Morphologically, necrosis was observed in 9 cases, angiocentric-angiodestructive growth in 3 cases, and pseudoepitheliomatous hyperplasia in 2 cases. Anaplastic cells predominated in all cases, with some displaying eccentric, horseshoe-shaped, or kidney-shaped nuclei (referred to as "Hallmark" cells). The morphology profile was monomorphic in 3 cases and polymorphic in 7 cases. Immunohistochemically, all cases tested positive for cytotoxic granule markers (TIA1 and granzymeB) and Epstein-Barr virus-encoded RNA. Cytoplasmic expression of CD3ε and CD56 was observed in 9 of 10 cases. Interestingly, most cases (7 of 8) exhibited variable expression of MuM1, ranging from 10% to 90%. All cases showed diffuse positivity for CD30 but were negative for ALK, resulting in 3 cases being initially misdiagnosed as ALK-negative ALCL. Compared with nonanaplastic cases, anaplastic cells predominant ENKTL had a significantly higher frequency of "B" symptoms, bone marrow involvement, hemophagocytic lymphohistiocytosis, and higher Ki67 proliferative index. These findings provide valuable information for pathologists, expanding their understanding of the cytologic spectrum of ENKTL. This rare variant of ENKTL, characterized by the predominance of anaplastic cells and diffuse CD30 expression, exhibits high aggressiveness and should be differentiated from ALK-negative ALCL. Awareness of this uncommon variant is crucial in preventing misdiagnosis and ensuring the timely initiation of therapy.

Hydroa Vacciniforme Lymphoproliferative Disorder in a Young Spanish Woman: An Infrequent Case With Fatal Outcome

ABSTRACT

Hydroa vacciniforme (HV) lymphoproliferative disorder is a rare NK/T-cell lymphoma mainly affecting children and with a clinical resemblance to HV, which is mostly reported in Latin American and some Asian countries. Overall, the mature T cell and NK-cell neoplasms are now grouped into 9 families based on diverse concepts: cell of origin/differentiation state, clinical scenario, disease localization, and cytomorphology. HV lymphoproliferative disorder is listed within the group of Ebstein Barr Virus-positive T-cell and NK-cell lymphoid proliferations and lymphomas of childhood according to the fifth edition of the World Health Organization Classification of mature lymphoid neoplasms. We report the extraordinary case of a 22-year-old white woman, native of Spain, first presented in 2016 when she started suffering from recurrent facial edema. Four years later, the disease progressed with lymph node spreading and a fatal outcome. Here, we describe the clinical and histological presentation of the lymphoma throughout its evolution. Cases like this can be difficult to classify posing a real challenge to clinicians and pathologists. So, it is vital to be aware of the rare presentation of this disease to be able to identify the clinical and histological picture to make a correct diagnosis and establish an early treatment.

Molecular and clinicopathological features of granzyme B-negative extranodal NK/T-cell lymphoma

Extranodal NK/T-cell lymphoma (ENKTL) generally expresses cytotoxic molecules, including granzyme B (GZMB), T-cell-restricted intracellular antigen-1 (TIA-1), and perforin; however, the expression of these molecules varies across cases. We performed gene expression profiling and identified unique biological and clinicopathological features of GZMB-negative ENKTL. We reviewed the clinicopathological characteristics of 71 ENKTL samples. Gene expression profiling on nine ENKTLs using multiplexed, direct, and digital mRNA quantification divided ENKTLs into Groups A (n = 7) and B (n = 2) through hierarchical clustering and t-distributed stochastic neighbor embedding. Group B was characterized by downregulation of genes associated with IL6-JAK-STAT3 signaling and inflammatory responses. GZMB mRNA expression was significantly downregulated in Group B. GZMB protein expression was evaluated with immunohistochemistry in all 71 ENKTLs, and expression data of Tyr705-phosphorylated STAT3 (pSTAT3) and MYC from our previous study was utilized. T-cell receptor gamma (TRG) gene rearrangement in the selected samples was also assessed using PCR. GZMB expression was higher in pSTAT3-positive (p = 0.028) and MYC-positive (p = 0.014) ENKTLs. Eighteen percent (13/71) of all ENKTLs were negative for GZMB (defined by positivity <10 %); patients with GZMB-negative ENKTLs were often in a higher clinical stage (p = 0.016). We observed no other correlations with clinical parameters or TRG rearrangement and no significant association between GZMB expression and survival. In conclusion, GZMB expression is highly heterogeneous in ENKTLs and is associated with the activation of the JAK-STAT3 pathway and higher MYC expression. GZMB-negative ENKTLs correlate with an advanced clinical stage, suggesting the potential utility of GZMB immunohistochemistry as a biomarker of ENKTL.

Updates in the Classification of T-cell Lymphomas and Lymphoproliferative Disorders

PURPOSE OF REVIEW

Mature T/NK-cell neoplasms comprise a heterogeneous group of diseases with diverse clinical, histopathologic, immunophenotypic, and molecular features. A clinically relevant, comprehensive, and reproducible classification system for T/NK-cell neoplasms is essential for optimal management, risk stratification, and advancing understanding of these diseases. Two classification systems for lymphoid neoplasms were recently introduced: the 5th edition of World Health Organization classification (WHO-HAEM5) and the 2022 International Consensus Classification (ICC). In this review, we summarize the basic framework and updates in the classification of mature T/NK-cell neoplasms.

RECENT FINDINGS

WHO-HAEM5 and ICC share basic concepts in classification of T/NK-cell neoplasms, emphasizing integration of clinical presentation, pathology, immunophenotype, and genetics. Major updates in both classifications include unifying nodal T-follicular helper-cell lymphomas into a single entity and establishing EBV-positive nodal T/NK-cell lymphoma as a distinct entity. However, some differences exist in taxonomy, terminology, and disease definitions. The recent classifications of mature T/NK-cell neoplasms are largely similar and provide new insights into taxonomy based on integrated clinicopathologic features.

The expression and clinical significance of PLK1/p-PLK1 protein in NK/T cell Lymphoma

AIMS

To investigate the expression of polo-like kinase 1 protein (PLK1) and its phosphorylation level (p-PLK1) in extranodal NK/T cell lymphoma (NKTCL) and their correlation with clinical characteristics and prognosis.

METHODS

We collected 40 cases of NKTCL (referred to as the experimental group), which received diagnoses at the First Affiliated Hospital of Zhengzhou University between January 2018 and October 2022. Concurrently, we assembled a control group, including 20 cases afflicted with nasopharyngeal mucosal lymphoid hyperplasia diseases during the same timeframe. We utilized immunohistochemical techniques to evaluate the levels of PLK1 and p-PLK1 expression in both the experimental and control groups. Subsequently, we conducted an analysis to identify disparities in their expression and explore their relationships with clinical characteristics and patient prognosis.

RESULTS

Among the 40 NKTCL patients, there were 27 males and 11 females, with a median age of 51 years (range 12-80 years). Compared to the control group, the tissue samples of NKTCL patients exhibited significantly elevated expression levels and active phosphorylation levels of PLK1 (P < 0.05). Correlation analysis of the immunohistochemical H score and Ki-67 positive rate of PLK1 and p-PLK1, revealed a significant positive correlation for both (P < 0.0001, each). No statistically significant differences were observed in the distribution of PLK1 and p-PLK1 expression in NKTCL patients with respect to gender, age, Ann Arbor stage, PINK-E score, B-symptoms, lactate dehydrogenase, β2-microglobulin, blood EBV-DNA, bone marrow invasion, and lymph node metastasis (p > 0.05). Grouping based on PLK1 and p-PLK1 immunohistochemical H-scores revealed that the high expression of PLK1 and p-PLK1 was associated with poor prognosis.

CONCLUSIONS

The expression levels and active phosphorylation levels of PLK1 were significantly increased in NK/T cell lymphoma, and patients with overexpression of PLK1 and p-PLK1 had a poorer prognosis.

Advances and challenges of immunotherapies in NK/T cell lymphomas

Natural killer (NK)/T cell lymphoma (NKTCL) is a rare subtype of Epstein-Barr virus (EBV)-associated non-Hodgkin lymphoma characterized by poor clinical outcomes. It is more common in East Asian and Latin American countries. Despite the introduction of asparaginase/pegaspargase-based chemotherapy, the prognosis of patients with advanced NKTCL needs to be improved, and few salvage treatment options are available for relapsed/refractory patients who fail chemotherapy. Although many unknowns remain, novel treatment strategies to further improve outcomes are urgently needed. Immunotherapy has emerged and shown favorable antitumor activity in NKTCL, including monoclonal antibodies targeting immune checkpoint inhibitors, other receptors on the cellular membrane, and cellular immunotherapy, which could enhance immune cells attack on tumor cells. In this review, we provide an overview of recent immunotherapy in NKTCL, focusing on programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1), cytotoxic T lymphocyte-associated protein 4 (CTLA-4), chimeric antigen receptor (CAR) T cells, EBV-specific cytotoxic T lymphocytes, immunomodulatory agents, and other targeted agents, as well as the current progress and challenges in the field.

Extranodal natural killer/T-cell lymphoma with hepatosplenic involvement: a retrospective study of a consecutive 14-year case series

Extranodal natural killer/T-cell lymphoma (ENKTL) with hepatosplenic involvement is rare, accounting for approximately 0.2% of ENKTL cases. The clinicopathologic features of ENKTL with hepatosplenic involvement are still poorly understood. Seven cases of ENKTL with hepatosplenic involvement were investigated retrospectively by clinical features, pathology, immunophenotype, genotype, Epstein-Barr virus (EBV) status, and survival analysis. The median age was 36 years; three patients (3/7) had a history of primary nasal ENKTL. Six cases (6/7) presented liver or spleen structures that were replaced by neoplasms, and the neoplastic cells displayed diffuse infiltration; one case (1/7) displayed neoplastic cells scattered in hepatic sinuses and portal areas. The cellular morphology and immunohistochemical features were similar to those of ENKTL involving other sites. Follow-up data were available in five of the seven patients. All five patients received first-line chemotherapy based on L-asparaginase. Three patients died, and two were still alive by the last follow-up. The median overall survival (OS) was 21 months. ENKTL with hepatosplenic involvement is rare, regardless of whether it is initial or secondary. There are two histopathologic patterns of ENKTL with hepatosplenic involvement, and L-asparaginase-based chemotherapy combined with AHSCT might yield good efficacy. Morphological features of ENKTL in the spleen and liver A The architecture of the spleen was affected, and dense infiltration of the neoplastic cells was observed in the left part; B Focal infiltration of the neoplastic cells was located in the red pulp; C Dense infiltration of the neoplastic cells in the liver, accompanied by fatty change of hepatocytes and congestion; D More neoplastic cells accumulated in sinusoidal region.

Extranodal NK-/T-cell lymphoma, nasal type: what advances have been made in the last decade?

Extranodal NK-/T-cell lymphoma (ENKTCL) is a rare and highly aggressive malignancy with significant racial and geographic variations worldwide. In addition to the formerly "nasal-type" initial description, these lymphomas are predominantly extranodal in origin and typically cause vascular damage and tissue destruction, and although not fully understood, Epstein-Barr virus (EBV) has an important role in its pathogenesis. Initial assessment must include a hematopathology review of representative and viable tumor areas without necrosis for adequate immunohistochemistry studies, including EBV-encoded small RNA (EBER) in situ hybridization (ISH). Positron emission tomography with 18-fluorodeoxyglucose (¹⁸F-FDG-PET/CT) for accurate staging is essential, and most patients will have localized disease (IE/IIE) at diagnosis. Apart from other T-cell malignancies, the best treatment even for localized cases is combined modality therapy (chemotherapy plus radiotherapy) with non-anthracycline-based regimens. For advanced-stage disease, l-asparaginase-containing regimens have shown improved survival, but relapsed and refractory cases have very poor outcomes. Nowadays, even with a better understanding of pathogenic pathways, up-front therapy is completely based on chemotherapy and radiotherapy, and treatment-related mortality is not low. Future strategies targeting signaling pathways and immunotherapy are evolving, but we need to better identify those patients with dismal outcomes in a pre-emptive way. Given the rarity of the disease, international collaborations are urgently needed, and clinical trials are the way to change the future.

An update on viral-induced cutaneous lymphoproliferative disorders. CME Part I

Viral-induced cutaneous T-cell lymphomas are an uncommon group of lymphoproliferative disorders characterized by a viral infection of T and natural killer (NK) cells. This group of cutaneous T-cell lymphomas is more commonly encountered in Asians and Native Americans from Central and South America compared with Western populations. Viral-associated lymphoproliferative disorders include a spectrum of entities that range from nonneoplastic lesions, such as chronic active Epstein-Barr virus infection and infective dermatitis to malignant diseases, such as extranodal NK/T-cell lymphoma, hydroa vacciniforme-like T-cell lymphoma, and adult T-cell leukemia/lymphoma. This review article will focus on hydroa vacciniforme-like lymphoproliferative disorder, extranodal NK/T-cell lymphoma, adult T-cell leukemia/lymphoma, lymphomatoid granulomatosis, and Epstein-Barr virus-positive mucocutaneous ulcers. We will review the pathogenesis of these conditions and the challenges of making a timely diagnosis in early-stage disease and discuss the common clinicopathologic manifestations, mutational landscape, and approaches to treat these highly aggressive and frequently lethal types of lymphoma.

Aggressive Cutaneous Lymphomas and Their Mimics

Cutaneous lymphomas encompass a heterogeneous group of neoplasms with a wide spectrum of clinical presentations, histopathologic features, and prognosis. Because there are overlapping pathologic features among indolent and aggressive forms and with systemic lymphomas that involve the skin, clinicopathologic correlation is essential. Herein, the clinical and histopathologic features of aggressive cutaneous B- and T-cell lymphomas are reviewed. Indolent cutaneous lymphomas/lymphoproliferative disorders, systemic lymphomas, and reactive processes that may mimic these entities are also discussed. This article highlights distinctive clinical and histopathologic features, increases awareness of rare entities, and presents new and evolving developments in the field.

Classification and challenges in the histopathological diagnosis of peripheral T-cell lymphomas, emphasis on the WHO-HAEM5 updates

Mature T-cell lymphomas represent neoplastic expansions of T-cell lymphocytes with a post-thymic derivation. Most of these tumors feature aggressive clinical behavior and challenging histopathological diagnosis and classification. Novel findings in the genomic landscape of T-cell lymphomas are helping to improve the understanding of the biology and the molecular mechanisms that underly its clinical behavior. The most recent WHO-HAEM5 classification of hematolymphoid tumors introduced novel molecular and histopathological findings that will aid in the diagnostic classification of this group of neoplasms. The current review article summarizes the most relevant diagnostic features of peripheral T-cell lymphomas with an emphasis on the updates that are incorporated at the WHO-HAEM5.

High-dose extended-field radiotherapy plus chemotherapy improved survival in extranodal NK/T-cell lymphoma in a real-life setting: results from the multicenter T-Cell Brazil Project

Extranodal natural-killer/T-cell lymphoma (ENKTL) is a rare and aggressive Epstein-Barr virus related mature T-cell and natural-killer malignancy. Although highly prevalent in South America, few studies covering data from this geographic location have been published. Therefore, this study aims to report clinical characteristics, prognostic factors, and outcomes in a multicenter cohort of ENKTL patients from Brazil. This retrospective, observational and multicenter study included 98 ENKTL patients treated during two decades in Brazil. Data were extracted from the T-Cell Brazil Project database. In our cohort, 59/98 patients (60.2%) were male, with a median age of 50 years. Sixty-two patients (63.3%) had B-symptoms, 26/98 (26.5%) had Eastern Cooperative Oncology Group scale ≥ 2; 16/98 (16.3%) presented extranasal disease and 34.7% (34/98) were advanced-stage (Ann Arbor/Cotswolds III/IV). The median follow-up for the whole cohort was 49 months, with an estimated 2-year overall survival (OS) and progression-free survival (PFS) of 51.1% and 17.7%, respectively. In early-stage disease (IE/IIE), the median OS was 21.8 months for patients treated with concurrent radiotherapy plus chemotherapy (CCRT-VIPD [etoposide/vp-16, ifosfamide, cisplatin and dexamethasone), 16.2 months for sequential chemoradiotherapy (SCRT) followed by asparaginase-based regimens, and 56.7 months for SCRT followed by CHOP-like (cyclophosphamide, doxorrubicin, vincristine and prednisone) treatments, p = 0.211. CCRT was associated with higher rates of early-mortality, hematological toxicity, and mucositis. Median OS was 8.2 months for patients with advanced-stage disease receiving regimens containing asparaginase compared to 3.2 months for anthracycline-based therapy, p = 0.851. Chemo-radiotherapy (CRT) regimens demonstrated better OS (p = 0.001) and PFS (p = 0.007) than chemotherapy alone. Multivariate analysis revealed anemia, relapsed/refractory (R/R) disease and radiotherapy omission as poor outcome predictors for OS. Lymphopenia and radiotherapy omission adversely affected PFS. Concerning progression of disease within 24-months (POD-24), clinical stage III/IV was a poor outcome predictor. In this real-life Brazilian cohort, ENKTL presented dismal outcomes. Radiation therapy was an independent factor for increased OS and PFS, but CCRT regimens were associated with higher toxicities. Polychemotherapy based on anti-multi drug resistant agents was not associated with survival benefit in either early or advanced-stage disease in our patient cohort.

Intravascular NK/T-Cell Lymphoma: What We Know about This Diagnostically Challenging, Aggressive Disease

Intravascular lymphoma is a form of lymphoid malignancy characterized by neoplastic cells growing almost exclusively within the lumina of small- to medium-sized blood vessels. Most cases are of B-cell origin with rare cases of natural killer or T-cell lineage. Extranodal sites are affected, mainly the skin and central nervous system, although any organ may be involved. Intravascular NK/T-cell lymphoma deserves special attention because of its clinicopathologic features and the need for adequate immunophenotyping combined with clonality test for a proper diagnosis. Moreover, intravascular NK/T-cell lymphoma is strongly linked to Epstein-Barr virus (EBV), which is considered to play a role in tumorigenesis and to be responsible for the aggressive behavior of the disease. In this paper, we review the current knowledge on this rare lymphoma and, in particular, the most recent advances about its molecular landscape. The main distinguishing features with other EBV-related entities, such as extranodal NK/T-cell lymphoma, EBV-positive primary nodal T/NK-cell lymphoma, and aggressive NK-cell leukemia, are discussed to help pathologists obtain the correct diagnosis and consequently develop an adequate and prompt therapy response.

Multiple Progressive Necrotic Lesions in a Young Man: A Quiz

Abstract is missing (Quiz)

Primary small intestinal extranodal NK/T cell lymphoma, nasal type with kidney involvement: a rare case report and literature review

Background

Extranodal NK/T cell lymphoma, nasal type (EN-NK/T-NT) is a rare and aggressive type of non-Hodgkin’s lymphoma. EN-NK/T-NT seldom occurs in the gastrointestinal tract, and renal involvement is relatively rare.

Case presentation

Here we report a case of primary small intestinal EN-NK/T-NT with kidney involvement. We present the case of a 71-year-old female who was admitted to our hospital for coronary heart disease with a fever of unknown origin. Laboratory examination showed renal impairment and PET/CT showed a locally thickened wall of the small intestine, abnormally increased FDG metabolism in the right lower abdomen, and multiple slightly high-density masses with abnormal increased FDG metabolism in the right kidney. The gross specimen showed a grayish-white lump located in the ileum approximately 15 cm away from the ileocecum, and two grayish-white lumps located in the upper and lower poles of the right kidney, respectively. The pathological diagnosis was EN-NK/T-NT. The patient died approximately 10 months after the operation.

Conclusion

EN-NK/T-NT is a rare type of non-Hodgkin’s lymphoma and may develop insidiously, with fever as the only clinical manifestation. The disease was found to be difficult to diagnose in the early stage, resulting in a highly aggressive clinical course and short survival time.

Nasal Extranodal Natural Killer/T-cell Lymphoma Imitating Squamous Cell Carcinoma: A Case Report

Nasal extranodal NK/T-cell lymphoma (NNKTL) is a lethal disease due to poor prognosis with rapid progress. A 56-year-old man complained of left nasal obstruction and blood-stained nasal drip for two months. Incisional biopsies were performed at the outpatient department three times, and the diagnosis of SCC was made. The patient underwent wide excision of the entire lesion via endoscopic sinus surgery with navigation. Final pathologic report revealed NNKTL. Pathological examination of the tumor revealed overlying epithelium presenting as pseudoepitheliomatous hyperplasia (PEH), which mimicked SCC invasion, with infiltration of atypical lymphocytes in the deeper sections. Immunohistochemistry supported the diagnosis of NNKTL. Chemoradiotherapy was administered, and a complete response was achieved at the two-year follow-up. The correct diagnosis of NNKTL is essential for prompt treatment and prevention of superfluous surgery. Although the link between PEH and NNKTL may lead to a misdiagnosis of SCC, multiple large and deep biopsies can prevent this dilemma. A biopsy showing ulceration or necrosis can indicate PEH and imply potential malignancy. Repeated biopsies and complete immunohistochemical studies are important for diagnosing NNKTL.

Cutaneous Involvement of Extranodal NK/T Cell Lymphoma, Nasal Type, a Clinical and Histopathological Mimicker of Various Skin Diseases

Background: Extranodal NK/T cell lymphoma, nasal type (ENK/T) with cutaneous involvement has various histopathological findings and diverse clinical manifestations. Methods: A retrospective study of cutaneous involvement of ENK/T lymphoma between 2006 and 2018 was conducted. Results: Twenty-two cases were eligible for this study. Twelve cases could be proven as secondary cutaneous involvement by ENK/T lymphoma, while the remaining could not be confirmed as primary cutaneous ENK/T lymphoma. The histopathological patterns included dermal and subcutaneous nodular infiltration pattern in 11/22 cases (50%), lobular panniculitis pattern in 6/22 cases (27.3%), interface dermatitis pattern in 4/22 cases (18.2%), and granulomatous dermatitis pattern in 1/22 case (4.5%). The median follow-up was 18.3 months. Overall, the one-year and five-year survival rates were 31.3% and 13.3%, respectively. Conclusions: A variety of histopathological patterns of cutaneous involvement by ENK/T lymphoma should be differentiated from other cutaneous lymphomas, dermatitis, and infection. When atypical medium or large-sized lymphoid cells are encountered within skin lesions, pathologists should realize these lesions can be ENK/T lymphoma, especially in cases with coexisting tumor necrosis or angioinvasion. A complete evaluation of the upper aerodigestive tract is mandatory to identify the occult primary site of ENK/T lymphoma before establishing primary cutaneous ENK/T lymphoma.

Genomic profiling identifies distinct genetic subtypes in extra-nodal natural killer/T-cell lymphoma

Extra-nodal NK/T-cell lymphoma, nasal type (ENKTCL) is a highly aggressive Epstein-Barr virus associated lymphoma, typically presenting in the nasal and paranasal areas. We assembled a large series of ENKTCL (n = 209) for comprehensive genomic analysis and correlative clinical study. The International Lymphoma Prognostic Index (IPI), site of disease, stage, lymphadenopathy, and hepatomegaly were associated with overall survival. Genetic analysis revealed frequent oncogenic activation of the JAK/STAT3 pathway and alterations in tumor suppressor genes (TSGs) and genes associated with epigenomic regulation. Integrated genomic analysis including recurrent mutations and genomic copy number alterations using consensus clustering identified seven distinct genetic clusters that were associated with different clinical outcomes, thus constituting previously unrecognized risk groups. The genetic profiles of ENTKCLs from Asian and Hispanic ethnic groups showed striking similarity, indicating shared pathogenetic mechanism and tumor evolution. Interestingly, we discovered a novel functional cooperation between activating STAT3 mutations and loss of the TSG, PRDM1, in promoting NK-cell growth and survival. This study provides a genetic roadmap for further analysis and facilitates investigation of actionable therapeutic opportunities in this aggressive lymphoma.

Genetic and immunohistochemical profiling of NK/T-cell lymphomas reveals prognostically relevant BCOR-MYC association

Extranodal NK/T-cell lymphoma, nasal type (ENKTL) is an Epstein-Barr virus-positive, aggressive lymphoma with a heterogeneous cell of origin and variable clinical course. Several clinical prognostic indices have been proposed for ENKTL; however, there are few pathological biomarkers. This multi-institutional study sought to identify histologically assessable prognostic factors. We investigated mutation profiles by targeted next-generation sequencing (NGS) and immunohistochemical assessments of expression of MYC, Tyr705-phosphorylated (p-)STAT3, and CD30 in 71 ENKTL samples. The median age of the patients was 66 years (range, 6-100). The most frequent mutations were in STAT3 (27%), JAK3 (4%), KMT2D (19%), TP53 (13%), BCOR (10%), and DDX3X (7%). Immunohistochemistry (IHC) revealed that ENKTLs with STAT3 mutations exhibited higher expression of pSTAT3 and CD30. BCOR mutations were associated with increased MYC expression. Univariate analysis in the entire cohort showed that stage (II, III, or IV), BCOR mutations, TP53 mutations, and high MYC expression (defined as ≥40% positive neoplastic cells) were associated with reduced overall survival (OS). Multivariate modeling identified stage (II, III, or IV) and high MYC expression as independent adverse prognostic factors. In a subgroup analysis of patients treated with anthracycline (AC)-free chemotherapy and/or radiotherapy (RT) with curative intent, BCOR but not high MYC expression was an independent adverse prognostic factor. In conclusion, activating STAT3 mutations are common in ENKTLs and are associated with increased CD30 expression. MYC overexpression is, at least in part, associated with deleterious BCOR mutations, and this BCOR-MYC linkage may have prognostic significance, underscoring the potential utility of IHC for MYC in risk stratification of patients with ENKTL.

Cellular Origins and Pathogenesis of Gastrointestinal NK- and T-Cell Lymphoproliferative Disorders

The intestinal immune system, which must ensure appropriate immune responses to both pathogens and commensal microflora, comprises innate lymphoid cells and various T-cell subsets, including intra-epithelial lymphocytes (IELs). An example of innate lymphoid cells is natural killer cells, which may be classified into tissue-resident, CD56bright NK-cells that serve a regulatory function and more mature, circulating CD56dim NK-cells with effector cytolytic properties. CD56bright NK-cells in the gastrointestinal tract give rise to indolent NK-cell enteropathy and lymphomatoid gastropathy, as well as the aggressive extranodal NK/T cell lymphoma, the latter following activation by EBV infection and neoplastic transformation. Conventional CD4+ TCRαβ+ and CD8αβ+ TCRαβ+ T-cells are located in the lamina propria and the intraepithelial compartment of intestinal mucosa as type 'a' IELs. They are the putative cells of origin for CD4+ and CD8+ indolent T-cell lymphoproliferative disorders of the gastrointestinal tract and intestinal T-cell lymphoma, NOS. In addition to such conventional T-cells, there are non-conventional T-cells in the intra-epithelial compartment that express CD8αα and innate lymphoid cells that lack TCRs. The central feature of type 'b' IELs is the expression of CD8αα homodimers, seen in monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), which primarily arises from both CD8αα+ TCRαβ+ and CD8αα+ TCRγδ+ IELs. EATL is the other epitheliotropic T-cell lymphoma in the GI tract, a subset of which arises from the expansion and reprograming of intracytoplasmic CD3+ innate lymphoid cells, driven by IL15 and mutations of the JAK-STAT pathway.

Extranodal Natural Killer/T-Cell Lymphomas: Current Approaches and Future Directions

Extranodal natural killer/T(NK/T)-cell lymphoma (ENKTL) is a rare subtype of non-Hodgkin lymphoma that typically presents with an isolated nasal mass, but a sizeable minority present with advanced stage disease and have a significantly poorer prognosis. Those with limited disease are standardly treated with chemotherapy and radiation while those with advanced stage disease are treated with L-asparaginase containing chemotherapy regimens. The addition of modern radiation therapy techniques and the incorporation of L-asparaginase into chemotherapy regimens have significantly improved outcomes in this disease, but relapses and death from relapsed disease remain frequent. Given the high rate of relapse, several novel therapies have been evaluated for the treatment of this disease. In this review, we explore the current standard of care for ENKTL as well as novel therapies that have been evaluated for its treatment and the biologic understanding behind these therapies.

CD30+ Lymphoproliferative Disorders as Potential Candidates for CD30-Targeted Therapies

CONTEXT.—

In the early 1980s, a monoclonal antibody termed Ki-1 was developed against a cell line derived from a patient with Hodgkin lymphoma. This antibody detected a limited number of benign activated lymphocytes in lymphoid tissue, whereas in Hodgkin lymphoma it appeared to be nearly specific for Reed-Sternberg cells and their mononuclear variants. Subsequent studies showed that Ki-1 expression defined a new type of lymphoma that was later designated anaplastic large cell lymphoma with or without anaplastic large cell kinase expression/translocation. In the past 30 years, numerous new lymphoma entities have been defined, many of which are variably positive for CD30. Many virally transformed lymphoproliferative disorders are also frequently positive for CD30.

OBJECTIVE.—

To illustrate the broad spectrum of CD30+ hematologic malignancies and to provide an update of CD30-targeted therapies.

DATA SOURCES.—

Personal experiences and published works in PubMed.

CONCLUSIONS.—

Because of its low expression in normal tissue, CD30 was studied as a therapeutic target for many years. However, the first functional humanized antibody against CD30 was developed only about 10 years ago. Brentuximab vedotin is a humanized anti-CD30 antibody linked to a cytotoxin, and was approved by the US Food and Drug Administration in 2012 for treating refractory Hodgkin lymphoma and anaplastic large cell lymphoma. Since then, the list of Food and Drug Administration-approved CD30-targeted hematologic malignancies has grown. Recently, the therapies using tumor antigen-specific chimeric antigen receptor T cells targeting CD30 have incited a great deal of enthusiasm and are studied in clinical trials.

PEG-Asparaginase Single-Agent Rescue in an Advanced Case of Monomorphic Epitheliotropic Intestinal T Cell Lymphoma

PURPOSE

MEITL is a very rare and highly aggressive peripheral T cell lymphoma with poor prognosis and for which there is no standard treatment. Treatment options for patients patients with relapsed/refractory disease are scarce and the choice of an appropriate rescue still represents an unmet need.

METHODS

Here, we report the case of a 65-year-old woman affected by MEITL, progressing after initial treatment with an anthracycline-based chemotherapy and surgery, who received single-agent PEG-asparaginase salvage therapy at our institution.

RESULTS

PEG-asparaginase single-agent rescue proved to be rapidly effective in controlling the disease and its associated paraneoplastic features. Nevertheless, toxicity was high and the patient died due to a treatment-related complication.

CONCLUSION

The case we described brings new evidences on the effectiveness of PEG-asparaginase therapy in MEITL patients. Whether PEG-asparaginase should be included in the treatment course of MEITL patients could be the subject of future studies.

Identification and targeting of the developmental blockade in extranodal natural killer/T cell lymphoma

Extranodal natural killer/T-cell lymphoma (ENKTL) is an aggressive, rare lymphoma of natural killer (NK) cell origin with poor clinical outcomes. Here we used phenotypic and molecular profiling, including epigenetic analyses, to investigate how ENKTL ontogeny relates to normal NK-cell development. We demonstrate that neoplastic NK cells are stably, but reversibly, arrested at earlier stages of NK-cell maturation. Genes downregulated in the most epigenetic immature tumors were associated with polycomb silencing along with genomic gain and overexpression of EZH2. ENKTL cells exhibited genome-wide DNA hypermethylation. Tumor-specific DNA methylation gains were associated with polycomb-marked regions, involving extensive gene silencing and loss of transcription factor binding. To investigate therapeutic targeting, we treated novel patient-derived xenograft (PDX) models of ENKTL with the DNA hypomethylating agent, 5-azacytidine. Treatment led to reexpression of NK-cell developmental genes, phenotypic NK-cell differentiation, and prolongation of survival. These studies lay the foundation for epigenetic-directed therapy in ENKTL.

SIGNIFICANCE

Through epigenetic and transcriptomic analyses of ENKTL, a rare, aggressive malignancy, along with normal NK-cell developmental intermediates, we identified that extreme DNA hypermethylation targets genes required for NK-cell development. Disrupting this epigenetic blockade in novel PDX models led to ENKTL differentiation and improved survival. This article is highlighted in the In This Issue feature, p. 85.

Recent Advances in the Diagnosis and Treatment of Natural Killer Cell Malignancies

Simple Summary

Natural killer (NK)/T-cell lymphomas are aggressive extranodal Epstein–Barr virus (EBV)-positive malignancies. They can be divided into three subtypes: nasal (involving the nose and upper aerodigestive tract), non-nasal (involving skin, gastrointestinal tract, testis and other organs) and disseminated (involving multiple organs). Lymphoma cells are positive for CD3ε, CD56, cytotoxic molecules and EBV-encoded small RNA. There is a predilection for Asian and Central/South American populations. Genome-wide association studies have identified lymphoma susceptibility loci in Asians. Positron emission tomography computed tomography and plasma EBV DNA quantification are crucial at diagnosis and follow-up. Stage I/II patients receive non-athracycline asparaginse-containing regimens, together with sequential/concurrent radiotherapy. Anthracycline-containing regimens are ineffective. Stage III/IV patients receive asparaginase-containing regimens, followed by allogeneic haematopoietic stem cell transplantation (HSCT). Autologous HSCT does not improve outcome. In relapsed/refractory patients, novel approaches include PD1/PD-L1 targeting, EBV-specific cytotoxic T-cells, and monoclonal antibodies. Small molecules including histone deacetylase inhibitors may be beneficial.

Abstract

Natural killer (NK)/T-cell lymphomas are aggressive malignancies. Epstein–Barr virus (EBV) infection in lymphoma cells is invariable. NK/T-cell lymphomas are divided into nasal, non-nasal, and disseminated subtypes. Nasal NK/T-cell lymphomas involve the nasal cavity and the upper aerodigestive tract. Non-nasal NK/T-cell lymphomas involve the skin, gastrointestinal tract, testis and other extranodal sites. Disseminated NK/T-cell lymphoma involves multiple organs, rarely presenting with a leukaemic phase. Lymphoma cells are positive for CD3ε (not surface CD3), CD56, cytotoxic molecules and EBV-encoded small RNA. There is a predilection for Asian and Central/South American populations. Genome-wide association studies have identified lymphoma susceptibility loci in Asian patients. Positron emission tomography computed tomography and plasma EBV DNA quantification are crucial evaluations at diagnosis and follow-up. Stage I/II patients typically receive non-athracycline regimens containing asparaginse, together with sequential/concurrent radiotherapy. Anthracycline-containing regimens are ineffective. Stage III/IV patients are treated with asparaginase-containing regimens, followed by allogeneic haematopoietic stem cell transplantation (HSCT) in suitable cases. Autologous HSCT does not improve outcome. In relapsed/refractory patients, novel approaches are needed, involving PD1/PD-L1 targeting, EBV-specific cytotoxic T-cells, and monoclonal antibodies. Small molecules including histone deacetylase inhibitors may be beneficial in selected patients. Future strategies may include targeting of signalling pathways and driver mutations.

The Pathologic and Genetic Characteristics of Extranodal NK/T-Cell Lymphoma

Extranodal NK/T-cell lymphoma is a neoplasm of NK cells or cytotoxic T cells presenting in extranodal sites, most often in the nasal cavity. The typical immunophenotypes are cCD3+, sCD3-, CD4-, CD5-, CD8-, CD16-, and CD56+ with the expression of cytotoxic molecules. Tumor subsets express NK cell receptors, CD95/CD95L, CD30, MYC, and PDL1. Virtually all the tumor cells harbor the EBV genome, which plays a key role in lymphomagenesis as an epigenetic driver. EBV-encoded oncoproteins modulate the host-cell epigenetic machinery, reprogramming the viral and host epigenomes using host epigenetic modifiers. NGS analysis revealed the mutational landscape of ENKTL, predominantly involving the JAK-STAT pathway, epigenetic modifications, the RNA helicase family, the RAS/MAP kinase pathway, and tumor suppressors, which indicate an important role of these pathways and this group of genes in the lymphomagenesis of ENKTL. Recently, three molecular subtypes were proposed, the tumor-suppressor/immune-modulator (TSIM), MGA-BRDT (MB), and HDAC9-EP300-ARID1A (HEA) subtypes, and they are well-correlated with the cell of origin, EBV pattern, genomic alterations, and clinical outcomes. A future investigation into the function and interaction of discovered genes would be very helpful for better understanding the molecular pathogenesis of ENKTL and establishing better treatment strategies.

Primary Gastrointestinal T-Cell Lymphoma and Indolent Lymphoproliferative Disorders: Practical Diagnostic and Treatment Approaches

Simple Summary

It is challenging for pathologists to diagnose primary gastrointestinal T-cell neoplasms. Besides the rarity of the diseases, the small biopsy material makes it more difficult to differentiate between non-neoplastic inflammation and secondary involvement of extra gastrointestinal lymphoma. Since this group of diseases ranges from aggressive ones with a very poor prognosis to indolent ones that require caution to avoid overtreatment, the impact of the diagnosis on the patient is enormous. Although early treatment of aggressive lymphoma is essential, the treatment strategy is not well established, which is a problem for clinicians. This review provides a cross-sectional comparison of histological findings. Unlike previous reviews, we summarized up-to-date clinically relevant information including the treatment strategies as well as practical differential diagnosis based on thorough literature review.

Abstract

Primary gastrointestinal (GI) T-cell neoplasms are extremely rare heterogeneous disease entities with distinct clinicopathologic features. Given the different prognoses of various disease subtypes, clinicians and pathologists must be aware of the key characteristics of these neoplasms, despite their rarity. The two most common aggressive primary GI T-cell lymphomas are enteropathy-associated T-cell lymphoma and monomorphic epitheliotropic intestinal T-cell lymphoma. In addition, extranodal natural killer (NK)/T-cell lymphoma of the nasal type and anaplastic large cell lymphoma may also occur in the GI tract or involve it secondarily. In the revised 4th World Health Organization classification, indolent T-cell lymphoproliferative disorder of the GI tract has been incorporated as a provisional entity. In this review, we summarize up-to-date clinicopathological features of these disease entities, including the molecular characteristics of primary GI T-cell lymphomas and indolent lymphoproliferative disorders. We focus on the latest treatment approaches, which have not been summarized in existing reviews. Further, we provide a comprehensive review of available literature to address the following questions: How can pathologists discriminate subtypes with different clinical prognoses? How can primary GI neoplasms be distinguished from secondary involvement? How can these neoplasms be distinguished from non-specific inflammatory changes at an early stage?

NK-/T-cell lymphomas

Natural killer/T-cell lymphoma (NKTL) is a sub-type of Epstein-Barr virus (EBV)-related non-Hodgkin lymphomas common in Asia and Latin America but rare elsewhere. Its pathogenesis is complex and incompletely understood. Lymphoma cells are transformed from NK- or T-cells, sometimes both. EBV-infection and subsequent genetic alterations in infected cells are central to NKTL development. Hemophagocytic syndrome is a common complication. Accurate staging is important to predict outcomes but there is controversy which system is best. More than two-thirds of NKTL lympohmas are localized at diagnosis, are frequently treated with radiation therapy only and have 5-year survival of about 70 percent. Persons with advanced NKTLs receive radiation therapy synchronously or metachronously with diverse multi-drug chemotherapy typically including L-asparginase with 5-year survival of about 40 percent. Some persons with widespread NKTL receive chemotherapy only. There are few data on safety and efficacy of high-dose therapy and a haematopoietic cell autotransplant. Immune therapies, histone deacetylase (HDAC)-inhibitors and other drugs are in early clinical trials. There are few randomized controlled clinical trials in NKTLs and no therapy strategy is clearly best; more effective therapy(ies) are needed. Some consensus recommendations are not convincingly evidence-based. Mechanisms of multi-drug resistance are considered. We discuss these issues including recent advances in our understanding of and therapy of NKTLs.

Gastrointestinal lymphoproliferative lesions: a practical diagnostic approach

The gastrointestinal tract (GI) is the primary site of lymphoproliferative lesions, spanning from reactive lymphoid hyperplasia to overt lymphoma. The diagnosis of these diseases is challenging and an integrated approach based on clinical, morphological, immunohistochemical and molecular data is needed. To reach to confident conclusions, a stepwise approach is highly recommended. Histological evaluation should first assess the benign versus neoplastic nature of a given lymphoid infiltrate. Morphological and phenotypic analyses should then be applied to get to a definite diagnosis.

This review addresses the key histological features and diagnostic workup of the most common GI non-Hodgkin lymphomas (NHLs). Differential diagnoses and possible pitfalls are discussed by considering distinct groups of lesions (i.e. small to medium B-cell NHLs; medium to large B-cell NHLs; T-cell NHLs; and mimickers of Hodgkin lymphoma). The key clinical and epidemiological features of each entity are also described.

Molecular Update and Evolving Classification of Large B-Cell Lymphoma

Simple Summary

The development of high-throughput technologies in recent years has increased our understanding of the molecular complexity of lymphomas, providing new insights into the pathogenesis of large B-cell neoplasms and identifying different molecular biomarkers with prognostic impact, that lead to the revision of the World Health Organization consensus classification of lymphomas. This review addresses the main histopathological and molecular features of large B-cells lymphomas, providing an overview of the main recent novelties introduced by the last update of the consensus classification.

Abstract

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell neoplasms with considerable clinical, biologic, and pathologic diversity. The application of high throughput technologies to the study of lymphomas has yielded abundant molecular data leading to the identification of distinct molecular identities and novel pathogenetic pathways. In light of this new information, newly refined diagnostic criteria have been established in the fourth edition of the World Health Organization (WHO) consensus classification of lymphomas, which was revised in 2016. This article reviews the histopathological and molecular features of the various aggressive B-cell lymphoma subtypes included in the updated classification.

Rare Diseases of the Nose, the Paranasal Sinuses, and the Anterior Skull Base

Due to their low incidence and thus resulting limited diagnostic criteria as well as therapeutic options, rare diseases of the nose, the paranasal sinuses, and the anterior skull base are a significant challenge. The value as of which a disease has to be considered as rare amounts to a maximum of 5 patients per 10 000 people. Within these diseases, however, there are extreme differences. Some rare or orphan diseases like for example the inverted papilloma belong to regularly diagnosed and treated diseases of larger departments of oto-rhino-laryngology whereas other rare diseases and malformations have only been described in less than 100 case reports worldwide. This fact emphasizes the necessity of bundling the available experience of diagnostics and therapy. The present article gives an overview about rare diseases of the nose, the paranasal sinuses, and the anterior skull base from the field of diseases/syndromes of the olfactory system, malformations of the nose and paranasal sinuses, ventilation and functional disorders as well as benign and malignant tumors. The classification and data on diagnostic and therapeutic options were established based on the current literature.

Algorithmic Approach to Fibroinflammatory Sinonasal Tract Lesions

Fibroinflammatory lesions of the sinonasal tract are one of the most common head and neck lesions submitted to surgical pathology. When the fibroinflammatory pattern represents the lesion (i.e., not surface reactive ulceration), an algorithmic approach can be useful. Separated into reactive, infectious, and neoplastic, and then further divided based on common to rare, this logical progression through a series of differential considerations allows for many of these lesions to be correctly diagnosed. The reactive lesions include chronic rhinosinusitis and polyps, granulomatosis with polyangiitis, and eosinophilic angiocentric fibrosis. Infectious etiologies include acute invasive fungal rhinosinusitis, rhinoscleroma, and mycobacterial infections. The neoplastic category includes lobular capillary hemangioma, inflammatory myofibroblastic tumor, and NK/T-cell lymphoma, nasal type. Utilizing patterns of growth, dominant cell types, and additional histologic features, selected ancillary studies help to confirm the diagnosis, guiding further clinical management.

Extranodal NK/T cell lymphoma, nasal type: An updated overview

Extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT) is an aggressive malignancy associated with Epstein-Barr virus infection, with a geographic and racial predilection for some Asian and Latin American countries. ENKTCL-NT manifests as a necrotic process affecting nasal or upper aerodigestive structures and, rarely, extranasal sites such as skin, and the gastrointestinal tract. ENKTCL-NT was characterized by its poor prognosis irrespective of clinical stage and therapy. However, during the last two decades, advances in its clinicopathologic, genetic and molecular characterization have been achieved, as have changes in the chemotherapy regimens that, in combination with radiotherapy, are significantly improving the survival of these patients, especially in initial stages. For these reasons, we present an overview of the historical background of ENKTCL-NT along with an updated review of its potential etiological factors, clinicopathologic and molecular features, as well as its prognostic models, current treatment protocols, and future directions on potential promising therapeutic approaches.

Nodal EBV+ cytotoxic T-cell lymphoma: A literature review based on the 2017 WHO classification

Nodal Epstein-Barr virus (EBV)-positive cytotoxic T-cell lymphoma (CTL) is a primary nodal peripheral T-cell lymphoma (PTCL) characterized by a cytotoxic phenotype and EBV on the tumor cells. This disease reportedly accounts for 21% of PTCL not otherwise specified (NOS). However, few nodal EBV+ lymphomas have been documented in detail. Nodal EBV+ CTL and nasal-type NK/T-cell lymphoma (NKTL) both exhibit cytotoxic molecule expression and EBV positivity on the tumor cells; however, nodal EBV+ CTL is characterized as a systemic disease without nasopharyngeal involvement, and exhibits a CD8+/CD56− phenotype distinct from NKTL. The clinicopathological uniqueness of nodal EBV+ CTL is further supported by its T-cell origin in most reported cases. In the 2008 WHO classification, it was unclear whether nodal EBV+ CTL should be classified as PTCL or NKTL. However, based on additional data, the 2017 revision classifies nodal EBV+ CTL as PTCL. In the present review, we focus on the clinicopathological characteristics of nodal EBV+ CTL, discuss the relationship between chronic active EBV infection and nodal EBV+ lymphoma, and highlight future perspectives regarding the treatment of this disease.

Brentuximab Vedotin in the Treatment of Peripheral T Cell Lymphoma and Cutaneous T Cell Lymphoma

PURPOSE OF REVIEW

The recent development of brentuximab vedotin (BV), an antibody-drug conjugate targeting CD30-positive cells, has led to therapeutic advances in the treatment of T cell lymphomas. In this review, we discuss key studies of BV in peripheral T cell lymphoma (PTCL) and cutaneous T cell lymphoma (CTCL) and highlight important questions for further investigation.

RECENT FINDINGS

Monotherapy with BV has proven to be effective and well tolerated in patients with relapsed/refractory (R/R) CD30-positive CTCL. BV has shown significant activity in R/R PTCL as well, with particularly durable responses in patients with anaplastic large cell lymphoma (ALCL). In a landmark phase III study (ECHELON-2), BV + CHP demonstrated superior progression-free and overall survival relative to CHOP as frontline therapy for patients with CD30-expressing PTCL, representing the first randomized trial demonstrating an overall survival benefit in PTCL. Though BV is overall well tolerated, peripheral neuropathy remains a clinically significant adverse effect. BV is a major therapeutic advance in the treatment of patients with R/R CTCL and of those with PTCL in both the R/R and frontline settings. Key ongoing areas of investigation include optimization of CD30 expression as a predictive biomarker as well as the role of BV in consolidation therapy.

BCL-XL inhibition by BH3-mimetic drugs induces apoptosis in models of Epstein-Barr virus-associated T/NK-cell lymphoma

Epstein-Barr virus (EBV)-associated T- and natural killer (NK)-cell malignancies, such as extranodal NK-/T-cell lymphoma (ENKTL), exhibit high chemoresistance and, accordingly, such patients have a poor prognosis. The rare nature of such cancers and nonmalignant T/NK lymphoproliferative disorders, such as chronic active EBV (CAEBV), has limited our understanding of the pathogenesis of these diseases. Here, we characterize a panel of ENKTL- and CAEBV-derived cell lines that had been established from human tumors to be used as preclinical models of these diseases. These cell lines were interleukin-2 dependent and found to carry EBV in a latency II gene-expression pattern. All cell lines demonstrated resistance to cell death induction by DNA damage-inducing agents, the current standard of care for patients with these malignancies. This resistance was not correlated with the function of the multidrug efflux pump, P-glycoprotein. However, apoptotic cell death could be consistently induced following treatment with A-1331852, a BH3-mimetic drug that specifically inhibits the prosurvival protein BCL-XL. A-1331852-induced apoptosis was most efficacious when prosurvival MCL-1 was additionally targeted, either by BH3-mimetics or genetic deletion. Xenograft models established from the ENKTL cell line SNK6 provided evidence that A-1331852 treatment could be therapeutically beneficial in vivo. The data here suggest that therapeutic targeting of BCL-XL would be effective for patients with EBV-driven T/NK proliferative diseases, however, MCL-1 could be a potential resistance factor.

Clinical characteristics and survival of extranodal natural killer/T-cell lymphoma: a single-center 12-year retrospective analysis

The characteristics and survival of 218 patients with extranodal natural killer/T-cell lymphoma (ENKTCL) were analyzed in this retrospective study. The median progression-free survival (PFS) and overall survival (OS) were 10.9 months and 50.5 months, respectively. Sequential chemoradiotherapy achieved a 74.5% overall response rate (ORR) and a 30.9% 5-year PFS rate in patients with localized stage. Asparaginase-containing protocols demonstrated superior prognosis in advanced cases, with a median FPS at 5.7 months, compared to 1.9 months without asparaginase. Initial treatment with P-GEMOX regimens showed superior ORR and PFS compared to the SMILE regimen, with lower toxicities. Hematopoietic stem cell transplantation (HSCT) improved the PFS and OS of refractory or relapsed (R/R) cases. PD-1/PD-L1 antibody could achieve a median PFS at 4.0 months and a median OS at 14.6 months in R/R patients for whom salvage therapies failed. High-risk PINK-E score was the only independent adverse prognostic factor for PFS and OS.

Intestinal NK/T cell lymphoma: A case report

BACKGROUND

The incidence of intestinal NK/T cell lymphoma (NKTCL) is extremely low, and the clinical symptoms are atypical, which makes it difficult to distinguish this disorder from Crohn's disease (CD), T lymphocyte proliferative disease, and other immune disorders. The misdiagnosis rate is high, and the patient's prognosis is poor.

CASE SUMMARY

In this case, the patient had repeated high fever, colonoscopy revealed multiple ulcers, and the initial diagnosis was CD. The patient’s condition did not improve after treatment with hormones and infliximab, and she eventually died. Positron emission tomographic-computed tomographic and B-ultrasound were performed in our hospital and showed that multiple lymph nodes were enlarged. Immunohistochemi-stry showed that CD3 and Epstein-Barr virus encoded RNA expression was positive. Colonoscopy, tissue biopsy, and histopathology showed intestinal focal mucosal infiltration of heterotypic lymphocytes with an abnormal immune phenotype. On the basis of the patient’s medical history, auxiliary examination, and pathological findings, digestive physicians and pathologists gave the diagnosis of NKTCL.

CONCLUSION

Clinicians need to improve their comprehensive knowledge of NKTCL, and combination of clinical symptoms, histological characteristics, as well as colonoscopy biopsies should be considered to improve the diagnosis and thereby reduce misdiagnosis.

Safety and Efficacy of Brentuximab Vedotin in the Treatment of Classic Hodgkin Lymphoma

Classical Hodgkin lymphoma (cHL) is a B-cell-derived lymphoid malignancy with the most favorable prognosis among various adult malignancies. However, once it becomes refractory disease to chemotherapy or relapses after high-dose chemotherapy (HDC) with autologous stem cell transplantation (ASCT), it is difficult to manage with conventional cytotoxic chemotherapy. The introduction of brentuximab vedotin (BV) has changed the treatment landscape of cHL in the past decade. Several studies demonstrated high efficacy of BV monotherapy in heavily treated patients with cHL relapsed or refractory after HDC/ASCT. Recent studies also reported high efficacy of concurrent or sequential combination of BV and chemotherapy in patients with transplant-eligible relapsed/refractory cHL at the second-line setting. In addition, a randomized phase III trial ECHELON-1 reported a positive result of BV in combination with AVD (doxorubicin, vinblastine, and dacarbazine) in patients with newly diagnosed advanced-stage cHL. In this review, we summarize available data of BV for cHL and discuss the current and future role of BV in the management of cHL.

Cardiac Involvement and Subsequent Death due to Extranodal NK/T Cell Cutaneous T-Cell Lymphoma: An Autopsy Case and Brief Review of the Literature

Cardiac tumors range from benign to high grade malignancies. The incidence of cardiac involvement either by primary, or secondary tumors during autopsy is reported to be extremely low. Extranodal NK/T-cell lymphoma (ENKTL), nasal type is an unusual type of lymphoma. The skin is the second most common site of involvement after the respiratory tract. We present a case of a 63-year-old male, who was recently diagnosed with ENKTL, nasal type, who received chemotherapy, and died without any evident cause. The corpse was referred for routine medicolegal examination. Macroscopical determination of the cause of death was not feasible and subsequent histopathological examination revealed heart infiltration by ENKTL that was found in vivo in cutaneous lesions. Similar infiltrations existed in the pancreatic tissue. To the best of our knowledge, myocardial infiltration of ENKTL, inducing severe myocardial lesions that eventually caused death, is rare, with limited cases reported in the literature.

A suggested immunohistochemical algorithm for the classification of T-cell lymphomas involving lymph nodes

T-cell lymphomas are a heterogeneous group of neoplasms derived from mature T lymphocytes. These neoplasms are uncommon and usually diagnostically challenging. The focus of this article is to suggest an immunohistochemistry-based, practical approach to assist in the diagnosis of nodal T-cell lymphomas. These neoplasms fall into two major groups: those with many CD30+ tumor cells (group A) and neoplasms that are negative or show only partial expression of CD30 (group B). The differential diagnosis of group A neoplasms mainly includes ALK+ anaplastic large-cell lymphoma (ALCL), ALK-negative ALCL, mycosis fungoides with CD30+ large-cell transformation, adult T-cell leukemia/lymphoma, extranodal T-cell lymphomas involving lymph nodes (usually regional), and peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). Group B neoplasms also include two groups based on the presence or absence of T follicular helper (TFH) markers. Those neoplasms expressing at least 2 TFH markers include angioimmunoblastic T-cell lymphoma, nodal PTCL with a TFH phenotype, and follicular T-cell lymphoma. Neoplasms expressing ≤1 TFH marker can be further subdivided based on the expression of CD8 and cytotoxic markers and mainly include PTCL-NOS and a series of unusual subsets including primary Epstein-Barr virus-positive nodal natural killer/T-cell lymphoma, PTCL-NOS with a cytotoxic immunophenotype, and γ/δ T-cell lymphomas. Using this algorithmic approach, we suggest that the pathologist can establish a diagnosis for most nodal T-cell lymphomas encountered in daily practice.

Mutational profile and EBV strains of extranodal NK/T-cell lymphoma, nasal type in Latin America

Extranodal NK/T-cell lymphoma (ENKTL) is an Epstein-Barr virus (EBV) associated lymphoma, prevalent in Asia and Latin America. Studies in Asian cohorts have identified some recurrent gene mutations in ENKTL; however, the mutational landscape of ENKTL in Latin America is unknown. In this study, we investigated the mutational profile and EBV strains of 71 ENKTL cases from Latin America (42 from Mexico, 17 from Peru, and 12 from Argentina) and compared it with Asian cohorts. The mutational analysis was performed by next generation sequencing (NGS) using an Ion AmpliSeq™ custom panel covering for the most frequently mutated genes identified in ENKTL. STAT3 was the most frequent mutated gene (16 cases: 23%), followed by MSN (10 cases; 14%), BCOR (9 cases; 13%), DDX3X (6 cases; 8%), TP53 (6 cases; 8%), MGA (3 cases; 4%), JAK3 (2 cases; 3%), and STAT5B (1 case; 1%). Mutations in STAT3, BCOR, and DDX3X were nearly mutually exclusive, suggesting different molecular pathways involved in the pathogenesis of ENKTL; whereas mutations in MGA, MSN, and TP53 were concomitant with other mutations. Most cases (75%) carried Type A EBV without the 30-bp LMP1 gene deletion. The overall survival was significantly associated with serum LDH level, Eastern Cooperative Oncology Group (ECOG) performance status, International Prognostic Index (IPI) score, and therapy (p < 0.05), but not associated with any mutation, EBV strain or deletion in EBV LMP1 gene. In conclusion, mutational analysis of ENKTL from Latin America reveals frequent gene mutations leading to activation of the JAK-STAT pathway (25%), mostly STAT3. Compared to Asian cohorts, BCOR, DDX3X  and TP53 mutations were also identified but with different frequencies. None of these mutations were associated with prognosis.

Extranodal NK/T-Cell Lymphomas: The Role of Natural Killer Cells and EBV in Lymphomagenesis

Natural killer (NK) cells are lymphocytes involved in innate and adaptive immune functions. They are the presumed cell of origin of distinct hematolymphoid malignancies, including aggressive NK-cell leukemia and extranodal NK/T-cell lymphoma (ENKTL). This review focuses on the role of NK cells and Epstein–Barr virus (EBV) in ENKTL pathogenesis.