Natural killer cell neoplasms: a distinctive group of highly aggressive lymphomas/leukemias

Outcomes and prognostic factors of patients with Extranodal NK T cell lymphoma (ENKTL)

The staging, prognostication, and treatment of ENKTL has evolved over the years with better understanding of the disease biology. There is significant heterogeneity in the treatment followed across the world. Literature from India have been few with small number of patients. We studied the outcomes and prognostic factors of patients with ENKTL treated between May 2010 and December 2021 at our center. A total of 78 patients diagnosed with ENKTL were treated at our center. L-asparaginase based chemotherapy was administered in 84% of the patients. Close to 2/3rd patients received SMILE chemotherapy. After a median follow-up of 30 months (18.5-41.4 months), the median relapse free survival and overall survival for the overall population was 45 months (12-118 months) and 45 months (14-118 months) respectively. By multivariate analysis, PINK score of 2-4, non-receipt of RT and non-achievement of CR were associated with poor survival.

A Case Report on Aggressive Natural Killer Cell Leukemia in a Pediatric Patient

Aggressive natural killer cell leukemia (ANKL) is a rare neoplastic malignancy, especially in pediatric populations with very few cases reported in the literature. It commonly presents with a rapidly declining clinical course and has a median survival of two months. We report the case of a 15-year-old female who presented with fever, hepatosplenomegaly, hemophagocytosis, and disseminated intravascular coagulation (DIC). The patient was ultimately diagnosed with ANKL but died after developing multiorgan failure and DIC prior to the initiation of any treatment. In this case report, we review and discuss the literature concerning the diagnosis and treatment of ANKL in pediatric patients.

Natural Killer-Like T-Cell Lymphoma: A Rare Cause of Acute Liver Failure

Acute liver failure is characterized by encephalopathy and disruption of hepatic function, often requiring liver transplantation to prevent fatal consequences. We present a 33-year-old man with recurrent lymphoma presenting with acute liver failure, which was initially thought to be from drug-induced liver injury associated with his chemotherapy medication, asparaginase. However, liver biopsy revealed malignant infiltration by lymphoma. The subtype of lymphoma was natural killer–like T-cell lymphoma, which is an uncommon variant, and has rarely been associated with hepatic infiltration. His condition rapidly worsened with development of multiorgan failure leading to death.

Multi-parametric single cell evaluation defines distinct drug responses in healthy hematologic cells that are retained in corresponding malignant cell types

Innate drug sensitivity in healthy cells aids identification of lineage specific anti-cancer therapies and reveals off-target effects. To characterize the diversity in drug responses in the major hematopoietic cell types, we simultaneously assessed their sensitivity to 71 small molecules utilizing a multi-parametric flow cytometry assay and mapped their proteomic and basal signaling profiles. Unsupervised hierarchical clustering identified distinct drug responses in healthy cell subsets based on their cellular lineage. Compared to other cell types, CD19⁺/B and CD56⁺/NK cells were more sensitive to dexamethasone, venetoclax and midostaurin, while monocytes were more sensitive to trametinib. Venetoclax exhibited dose-dependent cell selectivity that inversely correlated to STAT3 phosphorylation. Lineage specific effect of midostaurin was similarly detected in CD19⁺/B cells from healthy, acute myeloid leukemia and chronic lymphocytic leukemia samples. Comparison of drug responses in healthy and neoplastic cells showed that healthy cell responses are predictive of the corresponding malignant cell response. Taken together, understanding drug sensitivity in the healthy cell-of-origin provides opportunities to obtain a new level of therapy precision and avoid off-target toxicity.

EBV-Associated Lymphoproliferative Disorders: Update in Classification

Although about 90% of the world's population is infected by EBV only a small subset of the related infections result in neoplastic transformation. EBV is a versatile oncogenic agent involved in a multitude of hematopoietic, epithelial, and mesenchymal neoplasms, but the precise role of EBV in the pathogenesis of many of the associated lymphoid/histiocytic proliferations remains hypothetical or not completely understood. Additional studies and use of evolving technologies such as high-throughput next-generation sequencing may help address this knowledge gap and may lead to enhanced diagnostic assessment and the development of potential therapeutic interventions.

Epstein-Barr virus (EBV)-associated lymphoid proliferations, a 2018 update

Epstein-Barr virus (EBV) has been linked to many human neoplasms including hematopoietic, epithelial, and mesenchymal tumors. Since our original review of EBV-associated lymphoproliferative disorders in 2007, many advances and developments have been reported. In this review, we will examine the recent advances in EBV-associated lymphoid/histiocytic proliferations, dividing them into reactive, B cell, T/NK cell, immunodeficiency-related, and histiocytic/dendritic cell proliferations.

CD21-independent Epstein-Barr virus entry into NK cells

Extranodal natural killer (NK)/T-cell lymphoma is an aggressive malignant disease that is associated with Epstein-Barr viral (EBV) infection. To date, the mechanism of viral entry into NK cells remains uncertain. Here, we investigated this mechanism using human NK cells in vitro. CD21 mRNA expression, an EBV-entry receptor, was transiently detected in NK cells after exosome treatment, and levels decreased after further culture. CD21 protein expression was also transiently transferred to NK cells after co-culture with an EBV-positive Burkitt lymphoma cell line (Raji) via trogocytosis. However, EBV did not infect NK cells through CD21-mediated trogocytosis. Unexpectedly, when NK cell leukemia cells, as well as primary NK cells, were treated with viral supernatant, EBV genes, but not RNA, were detected in the NK cells, at latency stage 0. Therefore, these results suggest that EBV-NK cell infection results from the direct transfer of viral episomes, independent of EBV-positive B cells.

Primary Pulmonary Extranodal Natural Killer/T-cell Lymphoma, Nasal Type Presenting as Diffuse Ground Glass Opacities: a Case Report

Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTCL) is a rare type of lymphoma that accounts for only 5%-18% of all cases of non-Hodgkin lymphoma (NHL). In published series, 60%-90% of NK/T-cell lymphomas are localized to the nasal and upper airway. We describe a 55-year man who presented with cough, sputum, dyspnea on exertion, and a chest computed tomography scan shows diffuse ground glass opacities (GGOs), suggestive of an interstitial lung disease. He was treated with a corticosteroid and his symptoms improved. However, when the corticosteroid was tapered, his symptoms recurred. The patient underwent a surgical lung biopsy and ENKTCL was diagnosed. We present this case because ENKTCL involving only the lung is very rare but very informative. To our knowledge, our patient is the first case that primary pulmonary ENKTCL is presented with GGOs.

Classification and Treatment of Rare and Aggressive Types of Peripheral T-Cell/Natural Killer-Cell Lymphomas of the Skin

Background

The classification of cutaneous lymphomas has been contentious. Two major competing classifications were the World Health Organization (WHO) and the European Organization for Research and Treatment of Cancer (EORTC). The principal authors met for a consensus meeting resulted in a combined classification called WHO-EORTC Classification of Cutaneous Lymphoma.

Methods

We review the classification of “mature” or peripheral T-cell lymphoma (PTCL) with high predilection to the skin as published by the WHO-EORTC. We also highlight new information and changes from the previous classifications of cutaneous PTCL according to the WHO classification or the EORTC classification. Finally, the salient findings are compared with similar-looking nodal PTCLs with a high frequency of skin involvement.

Results

This review focuses on a rare group of cutaneous PTCLs other than mycosis fungoides or its variants. Changes from the previous classifications are discussed, and the rare group of nodal PTCLs with high predilection to the skin are presented. The salient findings, diagnostic features, and treatments are included, along with summary tables and clinical-histopathologic images.

Conclusions

This review may serve as a guide for hematologists, oncologists and dermatologists in the diagnosis and management of these rare, aggressive, and often difficult to diagnose lymphomas. Although cutaneous lymphomas are morphologically identical to systemic lymphomas, the former behave differently, require divergent management, and should be recognized as separate entities. The consensus WHO-EORTC classification presents unified terminology and definitions to promote conformity in diagnosing and treating these cases, to foster a multidisciplinary approach to these often-obscure diseases, and to lead to more advances in identifying molecular targets specific to these entities.

EBV-negative Aggressive NK-cell Leukemia/Lymphoma: Clinical, Pathologic, and Genetic Features

Aggressive natural killer cell leukemia (ANKL) is a systemic NK-cell neoplasm, almost always associated with Epstein-Barr virus (EBV). Rare cases of EBV-negative ANKL have been described, and some reports suggested more indolent behavior. We report the clinicopathologic, immunophenotypic, and molecular characteristics of 7 EBV-negative ANKL. All patients were adults, with a median age of 63 years (range 22 to 83 y) and an M:F ratio of 2.5:1. Five patients were White, 1 Black, and 1 Asian. All patients presented acutely, with fever (6/7), cytopenias (6/7), and splenomegaly (4/7). Four patients had lymphadenopathy, 4 had extranodal disease. Bone marrow involvement was present in 5, with hemophagocytosis in 3. Peripheral blood was involved in 5 with the neoplastic cells containing prominent azurophilic granules. By immunohistochemistry and/or flow cytometry, the tumor cells lacked surface CD3 and were positive for CD56 (7/7), CD2 (5/5), CD8 (3/7), CD30 (4/5), and granzyme-B (6/6). They were negative for CD4, CD5, βF1, TCRγ, LMP1, and EBV-encoded RNA. Polymerase chain reaction for TCRG clonality was polyclonal. Mutational analysis revealed missense mutations in the STAT3 gene in both cases studied. Median survival was 8 weeks from the onset of disease. One patient received allogeneic bone marrow transplant and is alive with no disease (follow-up 15 mo). EBV-negative ANKL exists but is rare. It tends to occur in older patients and is indistinguishable clinically and pathologically from EBV-positive ANKL, with a similar fulminant clinical course. The high prevalence of Asian patients seen with EBV-positive disease seems less evident with EBV-negative cases.

Clinical analysis of 42 cases of EBV-positive mature T/NK-cell neoplasms

The pathogenesis of Epstein-Barr virus-positive (EBV⁺) mature T-cell and natural killer (NK)-cell neoplasms is challenging to understand. The clinical features are diverse, with no typical manifestation. Therefore, it is important to analyze the association of the clinical characteristics and prognoses of patients with various factors associated with EBV⁺ T/NK-cell neoplasms, particularly extranodal NK/T cell lymphoma, systemic EBV⁺ T/NK cell lymphoproliferative disorders, aggressive NK cell leukemia and EBV⁺ peripheral T-cell lymphoma. Therefore, 42 cases of EBV⁺ T/NK-cell neoplasms with information on age, gender, fever, LDH level, complete blood count (CBC) and immunophenotype (CD5/CD20) were retrospectively analyzed to examine the clinical features, prognoses and related factors. It was found that patients ≤60 years old accounted for 86% of cases. The frequency of stage III/IV disease was higher in groups with pancytopenia (P=0.005), high LDH level (P=0.020), CD5-expression status (P=0.031) and fever (P=0.024). There were significant differences in the mean International Prognostic Index (IPI) scores according to the presence or absence of fever (P=0.022), elevated or normal lactose dehydrogenase (LDH) levels (P=0.001), and pancytopenia or normal complete blood count (CBC; P=0.046). Analysis of overall survival showed that CD5 expression, CBC, IPI scores and LDH levels were factors associated with OS. CD5 expression (P=0.003), CBC (P=0.003) and IPI scores (P=0.017) were identified to be important risk factors on the basis of Cox regression analysis. The mean survival time was longer in the CD5⁺, CD20⁺ and normal CBC groups, and there was no clear difference in survival time according to LDH level or fever. In summary, CD5 and CD20 may be prognostic factors in EBV⁺ T/NK lymphoid neoplasms, and CBC and fever are most likely to influence the IPI score and Ann Arbor stage.

Chronic active Epstein-Barr virus infection associated with hemophagocytic syndrome and extra-nodal natural killer/T-cell lymphoma in an 18-year-old girl: A case report

RATIONALE

Chronic active Epstein-Barr virus infection (CAEBV) associated with hemophagocytic syndrome (HPS) and extra-nodal natural killer (NK)/T-cell lymphoma (ENKL) is a rare life-threatening disorder. This disease is easily misdiagnosed because of its varied presentations.

PATIENT CONCERNS

An 18-year-old girl was admitted to our hospital with a history of edema in the lower limbs and intermittent fever lasting for more than 1 month. At admission, she had severe liver injury of unknown etiology. Laboratory test results revealed pancytopenia, hyperferritinemia, hypertriglyceridemia, and hypofibrinogenemia. Results of serologic tests for EBV were positive. Results of a skin biopsy indicated EBV-positive NK/T-cell lymphoma, and bone marrow aspiration revealed focal hemophagocytosis and atypical lymphoid cells.

DIAGNOSIS

On the basis of these findings, we diagnosed the case as extra-nodal NK/T-cell lymphoma-associated HPS (natural killer/T-cell lymphoma-associated hemophagocytic syndrome), which is commonly induced by CAEBV.

INTERVENTIONS

Treatment consisted of general management of hepatitis, supplemented with albumin and empirical antibiotic therapy.

OUTCOMES

The patient died from massive gastrointestinal hemorrhage a week after she was discharged from the hospital.

LESSONS

ENKL and HPS present with varied features and are generally fatal; therefore, clinicians should proceed with caution in suspected cases. HPS should be considered when the patient presents with fever, hepatosplenomegaly, pancytopenia, and liver failure. When HPS is suspected, clinicians should determine the underlying cause, such as severe infection, including infection with viruses such as EBV; genetic predisposition; or underlying malignancies, especially lymphoma because of its strong association with HPS.

Radiotherapy combined with chemotherapy versus radiotherapy alone for early stage nasal natural killer/T-cell lymphoma: a meta-analysis

OBJECTIVE

To compare the efficacy of radiotherapy (RT) plus chemotherapy (CMT) versus RT alone for early stage nasal natural killer (NK)/T-cell lymphoma.

METHODS

All the eligible studies were searched by PubMed, Medline, Embase and the Cochrane Library. The meta-analysis was performed to compare odds ratios (ORs) for overall survival (OS), disease-free survival (DFS) and progression-free survival (PFS).

RESULTS

Eight studies were included in the meta-analysis. Chemotherapy group did not significantly differ from RT group. The pooled OR and 95% confidence interval (CI) for 1-year, 3-year, 5-year and 10-year OS was 1.25 [0.84, 1.87], 1.10 [0.76, 1.58], 0.83 [0.59, 1.17] and 1.05 [0.70, 1.56]. In addition, the combined OR and 95% CI for 5-year DFS and PFS were 0.96 [0.53, 1.73] and 0.71 [0.45, 1.12].

CONCLUSIONS

The current evidence suggests that CMT was not superior to RT alone. Radiotherapy may be still the main method in the treatment of early stage nasal NK/T-cell lymphoma.

Extranodal NK/T cell lymphoma and aggressive NK cell leukaemia: evidence for their origin on CD56+bright CD16-/+dim NK cells

Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into extranodal NK/T cell lymphoma, nasal type (ENKTL) and aggressive NK cell leukaemia (ANKL). In order to propose their normal NK cell counterparts, we reviewed the literature on the phenotype of the neoplastic NK cells from five series of patients with ENKTL (n = 411) and seven series of patients with ANKL (n = 114) and compared with that of the normal and activated mature CD56 NK cell subsets. The tumour NK cells usually express brightly the CD56 adhesion molecule and CD94 lectin type killer receptor, and have an activation-related (cytoplasmic CD3ε, CD7, CD45RO, HLA-DR) phenotype; in contrast, CD16 and killer immunoglobulin-like receptors are frequently negative, and CD57 expression is almost never observed. These phenotypic features would suggest that ENKTL and ANKL cells do represent the neoplastic counterpart of the mature CD56 NK cells, which undergo activation and malignant transformation after Epstein-Barr virus infection.

Natural Killer T-Cell Lymphoma of the Tongue

Lymphoma, which represents about 5.4% of all neoplasms and, more significantly, 19% to 28% of malignant neoplasms, is the most common nonepithelial malignancy of the head and neck area in Koreans. Natural killer T-cell (NK/T-cell) lymphoma is a lymphoma of putative natural killer cell lineage. NK/T-cell neoplasms are generally rare, but they are more common in people of East Asian, Mexican, or South American descent. These neoplasms are highly aggressive and show a strong association with Epstein-Barr virus. The preferential site of extranodal NK/T-cell lymphoma is the nasal cavity, and there has been no report of NK/T-cell lymphoma developing from the tongue. We encountered a rare case of NK/T-cell lymphoma of the tongue, which we report with a review of the literature.

The legacy of the F344 rat as a cancer bioassay model (a retrospective summary of three common F344 rat neoplasms)

The Fischer 344 (F344) rat was used by the National Toxicology Program (NTP) for over 5 decades for toxicity and carcinogenicity studies. However, in 2006, the NTP decided to switch to a different rat stock due largely to high background control incidences of Leydig cell tumors (LCTs) and mononuclear cell leukemia (MNCL), also known as large granular lymphocytic (LGL) leukemia. In the current review, we aim (1) to provide a summary of NTP bioassays with treatment-associated effects involving MNCL and LCTs in addition to male F344-specific tunica vaginalis mesothelioma (TVM); (2) to describe important pathobiological differences between these F344 rat tumor responses and similar target tissue-tumor response in humans; and (3) to present the NTP reasons for switching away from the F344 rat. We show that due to the highly variable background incidence of F344 MNCL, more reliance on historical control data than is usual for most tumor responses is warranted to evaluate potential effect of any chemical treatment in this rat strain. The high spontaneous incidence of LCTs in the testes of male F344 rats has made this tumor endpoint of little practical use in identifying potential testicular carcinogenic responses. TVM responses in F344 rats have a biological plausible relationship to LCTs unlike TVM in humans. Given their high spontaneous background incidence and species-specific biology, we contend that MNCL and LCT, along with TVM responses, in F344 rat carcinogenicity studies are inappropriate tumor types for human health risk assessment and lack relevance in predicting human carcinogenicity.

Primary Thyroid Extranasal NK/T-Cell Lymphoma Associated With Good Outcome: A Case Report and Literature Review: A Care-Compliant Article

Most thyroid lymphomas are B-lineage, and T-cell lymphomas are rare. None of primary thyroid extranasal NK/T-cell lymphoma (NKTCL) has been reported in the literature. Here, we report a case of extranasal NKTCL exclusively arising in the thyroid in an 18-year-old Chinese.The patient presented with rapid anterior swelling at the neck and aggravated dyspnea for 2 months. Neck computer tomography scan revealed diffuse thyroid enlargement in the left lobe compressing the trachea. The thyroid function test was indicative of hypothyroidism. Gastroscopy demonstrated chronic nonspecific gastritis. Subtotal thyroidectomy was performed. Histological examination showed a diffuse infiltration of neoplastic lymphoid cells with an angiodestructive behavior. Immunophenotype is positive for CD2, CD56, CD43, and TIA-1, and typically negative for surface CD3. Epstein-Barr virus-encoded small RNAs were detected in tumor cells. A diagnose of primary thyroid extranasal NKTCL-N lymphoma was confirmed by the findings.The patient was treated with CHOP-L combination chemotherapy followed by local radiotherapy, and tolerated the modality well. The patient has been in remission for 28 months so far.To our knowledge, this is the first case report of primary extranasal NKTCL exclusively arising in the thyroid. The case has a relatively good treatment outcome with timely diagnosis and multimodality approach.

Extranodal natural killer/T-cell lymphoma, nasal type: A great pretender

Extranodal natural killer/T-cell lymphoma, nasal type (ENKTCL) is a rare Epstein–Barr virus associated lymphoma seen predominantly in Asian population with a 5 years survival rate ranging from 10% to 75% depending on the stage of presentation. In this case report, we describe an unusual presentation of ENKTCL, which in its early stages was clinically misdiagnosed as buccal space infection and later on histologically as inflammatory myofibroblastic pseudotumor owing to manifold reasons. Postoperative biopsy specimen showed characteristic feature of ENKTCL both histologically and immunophenotypically. This case report underlines the importance of adequate sampling and the unusual presentation of ENKTCL nasal type with oral manifestations.

Primary Esophageal Extranasal NK/T Cell Lymphoma With Biphasic Morphology: A Case Report and Literature Review

We report a case of esophageal extranasal NK/T cell lymphoma with biphasic morphologic features revealed by a deep large piecemeal biopsy. A 40-year-old man present with pharyngalgia, dysphagia, recurrent fever, and 5-kg weight loss for 8 months. Endoscopy demonstrated progressing longitudinal ulcers and mucosal bridges along the esophagus. The first and second biopsies obtained superficial mucosa with scattered bland-looking small lymphocytes. A subsequent large piecemeal snare abscission for biopsy showed atypical lymphoid cells infiltrating into the deep lamina propria and muscularis mucosae, whereas the superficial lamina propria was highly edematous with scant small lymphocytes. Immunohistochemical studies confirmed that both underlying atypical cells and superficial small lymphocytes were neoplastic, sharing an identical immunophenotype: positive for CD2, CD3, CD43, CD8, CD56, TIA-1 and granzyme B. Epstein-Barr virus-encoded small RNAs were found in both cells. The histologic findings were diagnostic of primary esophageal extranasal NK/T cell lymphoma. However, the patient developed bone marrow depression during chemotherapy and died of massive cerebral hemorrhage after the first cycle of chemotherapy. Primary esophageal extranodal NK/T cell lymphoma nasal type is extremely rare. We show the biphasic morphology of this disease, which highlights the importance of deep biopsy for accurate diagnosis.

A TNM Staging System for Nasal NK/T-Cell Lymphoma

Ann Arbor stage has limited utility in the prognostication and treatment decision making in patients with NK/T-cell lymphoma (NKTCL), as NKTCL is almost exclusively extranodal and the majority is localized at presentation for which radiotherapy is the most important treatment and local invasiveness is the most important prognostic factor. In this study, we attempted to establish a TNM (Tumor-Node-Metastasis) staging system for nasal NKTCL (N-NKTCL). The staging rules of other head and neck cancers were used as reference along with the data of our 271 eligible patients. The primary tumor was classified into T1 to T4, and cervical lymph node metastasis was classified into N0 to N2 according to the extent of involvement. Any lesions outside the head and neck were classified as M1. N-NKTCL thereby was classified into four stages: stage I comprised T1-2N0M0; stage II comprised T1-2N1M0 and T3N0M0; stage III comprised T3N1M0, T1-3N2M0, and T4N0-2M0; and stage IV comprised TanyNanyM1. This staging system showed excellent performance in prognosticating survival. In the current series, the 5-year survival rates of patients with stages I, II, III, and IV N-NKTCL were 92%, 64%, 23%, and 0, respectively. Moreover, the predictive value of several currently used factors was abrogated in the presence of the TNM stage. The TNM staging system is highly effective in stratifying tumor burden and survival risk, which may have significant implications in the treatment decision making for patients with N-NKTCL.

Aggressive mature natural killer cell neoplasms: report on a series of 12 European patients with emphasis on flow cytometry based immunophenotype and DNA content of neoplastic natural killer cells

We report 12 cases of aggressive natural killer (NK) cell neoplasms diagnosed in Portugal, with emphasis on flow cytometry. Ten patients had extranodal NK/T cell lymphoma, nasal type and two had aggressive NK cell leukemia, and seven were men and five were women, with a median age of 50 years. NK cells brightly expressed the CD56 adhesion molecule and CD94 lectin type killer receptor and had an activation-related HLA-DR+ CD45RA+ CD45RO+ immunophenotype, in most cases. In contrast, dim CD16 expression was found in a minor proportion of cases, whereas CD57 and the CD158a and CD158e1 killer immunoglobulin-like receptors were negative. One-third of cases showed a hyperploid DNA content and nearly all had a very high S-phase proliferative rate. The phenotypic features of the neoplastic NK cells would suggest that they represent the transformed counterpart of the CD56 + bright NK cells that circulate in normal blood.

Distinguishing T-cell Large Granular Lymphocytic Leukemia from Reactive Conditions: Laboratory Tools and Challenges in Their Use

This article focuses on the challenges of diagnosing T-cell large granular leukemia and distinguishing it from benign reactive conditions, as well as more aggressive neoplasms of cytotoxic lymphocytes. No single laboratory method is sufficient to make the diagnosis, but instead a combination of flow cytometry, genetic studies, and bone marrow immunohistochemistry must be used.

Aggressive mature natural killer cell neoplasms: from epidemiology to diagnosis

Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into NK/T cell lymphoma, nasal type (NKTCL), aggressive NK-cell leukemia (ANKCL) and chronic lymphoproliferative disorders of NK-cells, the latter being considered provisionally. NKTCL and ANKCL are rare diseases, with higher prevalence in Asia, Central and South America. Most NKTCL present extranodal, as a destructive tumor affecting the nose and upper aerodigestive tract (nasal NKTCL) or any organ or tissue (extranasal NKTCL) whereas ANKCL manifests as a systemic disease with multiorgan involvement and naturally evolutes to death in a few weeks. The histopathological hallmark of these aggressive NK-cell tumors is a polymorphic neoplastic infiltrate with angiocentricity, angiodestruction and tissue necrosis. The tumor cells have cytoplasmatic azurophilic granules and usually show a CD45(+bright), CD2(+), sCD3(-), cytCD3epsilon(+), CD56(+bright), CD16(−/+), cytotoxic granules molecules(+) phenotype. T-cell receptor genes are in germ-line configuration. Epstein-Barr virus (EBV) -encoded membrane proteins and early region EBV RNA are usually detected on lymphoma cells, with a pattern suggestive of a latent viral infection type II. Complex chromosomal abnormalities are frequent and loss of chromosomes 6q, 11q, 13q, and 17p are recurrent aberrations. The rarity of the NK-cell tumors limits our ability to standardize the procedures for the diagnosis and clinical management and efforts should be made to encourage multi-institutional registries.

Resveratrol induces cell cycle arrest and apoptosis in malignant NK cells via JAK2/STAT3 pathway inhibition

Natural killer (NK) cell malignancies, particularly aggressive NK cell leukaemias and lymphomas, have poor prognoses. Although recent regimens with L-asparaginase substantially improved outcomes, novel therapeutic approaches are still needed to enhance clinical response. Resveratrol, a naturally occurring polyphenol, has been extensively studied for its anti-inflammatory, cardioprotective and anti-cancer activities. In this study, we investigated the potential anti-tumour activities of resveratrol against the NK cell lines KHYG-1, NKL, NK-92 and NK-YS. Resveratrol induced robust G0/G1 cell cycle arrest, significantly suppressed cell proliferation and induced apoptosis in a dose- and time-dependent manner for all four cell lines. In addition, resveratrol suppressed constitutively active STAT3 in all the cell lines and inhibited JAK2 phosphorylation but had no effect on other upstream mediators of STAT3 activation, such as PTEN, TYK2, and JAK1. Resveratrol also induced downregulation of the anti-apoptotic proteins MCL1 and survivin, two downstream effectors of the STAT3 pathway. Finally, resveratrol induced synergistic effect on the apoptotic and antiproliferative activities of L-asparaginase against KHYG-1, NKL and NK-92 cells. These results suggest that resveratrol may have therapeutic potential against NK cell malignancies. Furthermore, our finding that resveratrol is a bonafide JAK2 inhibitor extends its potential benefits to other diseases with dysregulated JAK2 signaling.

Cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in the treatment of stage IE/IIE extranodal natural killer/T cell lymphoma, nasal type: 13-year follow-up in 135 patients

We conducted a retrospective study of 135 patients of stage IE/IIE extranodal natural killer/T cell lymphoma, nasal type (ENKTL) treated with CHOP as induction chemotherapy to find some valuable prognostic factors and analyze the usefulness of International Prognostic Index (IPI) and Korean Prognostic Index (KPI) in predicting prognosis. Most of the patients were in the low-risk group (IPI score 0-1). Complete remission (CR) after induction chemotherapy was achieved in 31.8 % of the patients, which increased to 69.6 % after radiotherapy. The 2-, 5-, and 10-year overall survival (OS) rates were 60, 48, and 43 %, respectively. Patients with better performance status (ECOG 0-1), normal serum LDH level, without local invasiveness, low KPI scores, and IPI score of 0 had significantly better overall survival (P < 0.05) in univariate analysis. Using multivariate analysis, we identified serum LDH level, ECOG PS score and local invasiveness to be independent prognostic factors. In conclusion, ENKTL is an aggressive lymphoma that shows heterogeneity. The IPI and KPI score systems should be improved further to classify patients into different groups, and should be validated in larger prospective trials. Due to the multi-drug resistance mechanism of ENKTL, CHOP is no longer the state of art and novel drugs should be incorporated into future treatments.

HIV-associated gastric natural killer/T-cell lymphoma

Natural killer (NK)/T-cell lymphoma is a rare form of non-Hodgkin's lymphoma that is seen with increased frequency in HIV infection and in transplant recipients. This case report describes an unusual case of extranodal NK/T-cell lymphoma in a patient with advanced HIV disease in which gastric involvement was a significant feature.

An algorithmic approach to the diagnosis of NK and T cell lymphomas

Lymphomas of natural killer (NK) and T cell lineages are uncommon disorders, although as a group they are more usually encountered in Asia compared to Western populations. In part due to their rarity, diagnosis and classification of T cell lymphomas often pose a challenge to clinicians and pathologists. Although there are morphological features that are characteristic of certain subtypes, correct classification of NK and T cell neoplasms relies heavily on the immunophenotype. With few exceptions, non-random genetic alterations such as translocations are less often seen in T cell neoplasms, adding to the diagnostic difficulty. Given these limitations, pathological diagnosis and classification of NK and T cell lymphomas are anything but straightforward. This paper attempts to present a practical algorithmic approach for the general pathologist who is confronted with these neoplasms.

Diagnosis of a multicentric extranodal nasal-type natural killer T-cell lymphoma made with an anterior chamber tap

PURPOSE

To report the case of an unusual multicentric Epstein-Barr virus (EBV)-associated extranodal nasal-type natural killer T-cell lymphoma masquerading as unilateral panuveitis, diagnosed with an anterior chamber tap.

METHODS

The clinical history and the morphological, immunohistochemical, and molecular features of a 51-year-old white man with left severe panuveitis were retrospectively evaluated.

RESULTS

The patient initially presented with a 3-month history of recalcitrant sinusitis and new onset of unilateral loss of vision. Clinical examination revealed right peripheral facial nerve palsy, severe panuveitis of the left eye, and nasopharyngeal obstruction. Anterior chamber aspirates were examined. The combination of the presence of small- to intermediate-size lymphocyte proliferation, moderate elevation of the interleukin-10 level on cytokine profiling, and slightly positive polymerase chain reaction for EBV in the aqueous humor indicated an EBV-induced nasal-type natural killer T-cell lymphoma. Transnasal biopsy revealed the presence of numerous irregular lymphoma cells with positive staining for CD3, CD56, EBV-encoded RNA in situ hybridization, and negative staining for CD4, CD8, and CD1a. Lumbar puncture, cerebral magnetic resonance imaging, thoracoabdominal computed tomography, and upper digestive tract endoscopy revealed meningeal, renal, adrenal, and digestive involvement. Massive hemorrhage of the upper digestive tract caused rapid death.

CONCLUSION

Extranodal nasal-type natural killer T-cell lymphoma is a very uncommon disease that may present acutely, sometimes as pseudouveitis. Simple investigations such as anterior chamber aspirates for cytological examination, reinforced by cytokine profiling and viral polymerase chain reaction looking for EBV, may provide a rapid diagnosis, necessary given the poor prognosis of the disease. To our knowledge, and after extensive review of the literature, we did not find another case report diagnosing this entity by anterior chamber paracentesis.

Pathophysiologic mechanisms and management of neutropenia associated with large granular lymphocytic leukemia

Large granular lymphocyte (LGL) syndrome includes a spectrum of clonal T cell and natural killer cell chronic lymphoproliferative disorders. These conditions are thought to arise from chronic antigenic stimulation, while the long-term survival of the abnormal LGLs appears to be sustained by resistance to apoptosis and/or impaired survival signaling. T-cell LGL (T-LGL) leukemia is the most common LGL disorder in the Western world. Despite its indolent course, the disease is often associated with neutropenia, the pathogenesis of which is multifactorial, comprising both humoral and cytotoxic mechanisms. This article addresses the pathogenesis of T-LGL leukemia and natural killer cell chronic lymphoproliferative disorder, as well as that of T-LGL leukemia-associated neutropenia. Furthermore, as symptomatic neutropenia represents an indication for initiating treatment, available therapeutic options are also discussed.

Therapeutic efficacy of FTY720 in a rat model of NK-cell leukemia

NK-cell leukemia is a clonal expansion of NK cells. The illness can occur in an aggressive or chronic form. We studied cell lines from human and rat NK-cell leukemias (aggressive NK-cell leukemia) as well as samples from patients with chronic NK-cell leukemia to investigate pathogenic mechanisms. Here we report that Mcl-1 was overexpressed in leukemic NK cells and that knockdown of Mcl-1 induced apoptosis in these leukemic cells. In vitro treatment of human and rat NK leukemia cells with FTY720 led to caspase-dependent apoptosis and decreased Mcl-1 expression in a time- and-dose-dependent manner. These biologic effects could be inhibited by blockade of reactive oxygen species generation and the lysosomal degradation pathway. Lipidomic analyses after FTY720 treatment demonstrated elevated levels of sphingosine, which mediated apoptosis of leukemic NK cells in vitro. Importantly, systemic administration of FTY720 induced complete remission in the syngeneic Fischer rat model of NK-cell leukemia. Therapeutic efficacy was associated with decreased expression of Mcl-1 in vivo. These data demonstrate that therapeutic benefit of FTY720 may result from both altered sphingolipid metabolism as well as enhanced degradation of a key component of survival signaling.

Extranodal NK/T-cell lymphoma presenting with primary cardiac involvement

Primary cardiac lymphoma is extremely uncommon. We report a case of a 54 year old Caucasian male with a history of non-small cell lung cancer treated by surgical resection who presented with chest pain and dyspnea on exertion. Computerized tomography (CT) imaging confirmed a 7.8×3.8 cm right atrial soft tissue mass infiltrating the lateral wall of the right atrium, and a 5 cm pericardiophrenic mass. Echocardiography confirmed a moderate pericardial effusion without tamponade physiology. Percutaneous biopsy of the pericardiophrenic mass revealed pathologic features diagnostic of NK/T-cell lymphoma. He received CHOP chemotherapy with some improvement in symptoms, but experienced radiographic progression after 2 cycles. He received palliative involved field radiotherapy but developed new sites of progressive disease within the abdomen and died shortly after completing radiotherapy. NK/T-cell lymphomas are aggressive tumors that may present with unusual extranodal disease sites. Prompt diagnosis with consideration for referral to a specialty center with experience in treatment of these rare tumors may offer the greatest potential for improving treatment outcomes.

Efficacy of L-asparaginase with methotrexate and dexamethasone (AspaMetDex regimen) in patients with refractory or relapsing extranodal NK/T-cell lymphoma, a phase 2 study

Extranodal NK/T-cell lymphoma, nasal type, is a rare and highly aggressive disease with a grim prognosis. No therapeutic strategy is currently identified in relapsing patients. We report the results of a French prospective phase II trial of an L-asparaginase-containing regimen in 19 patients with relapsed or refractory disease treated in 13 centers. Eleven patients were in relapse and 8 patients were refractory to their first line of treatment. L-Asparaginase–based treatment yielded objective responses in 14 of the 18 evaluable patients after 3 cycles. Eleven patients entered complete remission (61%), and only 4 of them relapsed. The median overall survival time was 1 year, with a median response duration of 12 months. The main adverse events were hepatitis, cytopenia, and allergy. The absence of antiasparaginase antibodies and the disappearance of Epstein-Barr virus serum DNA were significantly associated with a better outcome. These data confirm the excellent activity of L-asparaginase–containing regimens in extranodal NK/T-cell lymphoma. L-Asparaginase–based treatment should thus be considered for salvage therapy, especially in patients with disseminated disease. First-line L-asparaginase combination therapy for extranodal NK/T-cell lymphoma warrants evaluation in prospective trials. This trial is registered at www.clinicaltrials.gov as #NCT00283985.

Treatment of Aggressive NK-Cell Leukemia: A Case Report and Review of the Literature

Aggressive NK-cell leukemia is a rare malignancy with neoplastic proliferation of natural killer cells. It often presents with constitutional symptoms, a rapid declining clinical course, and a poor prognosis with a median survival of a few months. The disease is usually resistant to cytotoxic agents, and no treatment has emerged as the standard of care for these patients. We report a case of an 18-year-old male who obtains complete remission following two lines of combination chemotherapy. We describe in details our regimens for induction chemotherapy and perform a review of existing literature concerning treatment of aggressive NK-cell leukemia.

Primary nasal-type natural killer/T-cell lymphoma of pterygopalatine fossa

Primary tumors that originated from the pterygopalatine fossa are seen rarely. In this paper, the case of a 69-year-old woman who complained of a 2-month history of headache, extending to the left part of the face, teeth, and shoulder, is reported. She had undergone right total mastectomy and axillar dissection of a spindle cell-type metaplastic carcinoma of the breast 1 year ago. Computed tomographic and magnetic resonance images showed a mass originating from the pterygopalatine fossa. Pathologic examination of the biopsy specimen of the mass revealed a nasal-type extranodal natural killer/T-cell lymphoma with CD45 and intense CD56 staining. Our case shows that a nasal-type extranodal natural killer/T-cell lymphoma should be thought in mind for the differential diagnosis of primary tumors of the pterygopalatine fossa.

Targeting of survivin by nanoliposomal ceramide induces complete remission in a rat model of NK-LGL leukemia

The natural killer (NK) type of aggressive large granular lymphocytic (LGL) leukemia is a fatal illness that pursues a rapid clinical course. There are no effective therapies for this illness, and pathogenetic mechanisms remain undefined. Here we report that the survivin was highly expressed in both aggressive and chronic leukemic NK cells but not in normal NK cells. In vitro treatment of human and rat NK-LGL leukemia cells with cell-permeable, short-chain C₆-ceramide (C₆) in nanoliposomal formulation led to caspase-dependent apoptosis and diminished survivin protein expression, in a time- and dose-dependent manner. Importantly, systemic intravenous delivery of nanoliposomal ceramide induced complete remission in the syngeneic Fischer F344 rat model of aggressive NK-LGL leukemia. Therapeutic efficacy was associated with decreased expression of survivin in vivo. These data suggest that in vivo targeting of survivin through delivery of nanoliposomal C₆-ceramide may be a promising therapeutic approach for a fatal leukemia.

Advances in the management and monitoring of extranodal NK/T-cell lymphoma, nasal type

Extranodal natural killer (NK)/T-cell lymphoma, nasal type, has a unique geographic distribution. Its pathology is characterized by marked angio-invasion and tissue necrosis. A typical NK-cell phenotype is usually present: CD2(+), CD3 epsilon+, CD56(+), cytotoxic molecules+ and Epstein-Barr virus (EBV)+. Magnetic Resonance Imaging helps to clearly define the local involvement. Positron Emission Tomography helps to demonstrate system spread. Various prognostic variables (International Prognostic Index or the Korean Prognostic Index) should be documented. This may include quantification of plasma EBV DNA. For localized nasal disease, radiotherapy is important, although chemotherapy is often added. Sustainable remission is observed in over half of these patients. For extra-nasal or disseminated disease, systemic chemotherapy becomes the mainstay and the prognosis is usually poor. Doxorubicin-containing regimens are not entirely satisfactory and L-asparaginase containing regimens are being investigated. Patients with poor prognostic features may be considered for an early autologous haematopoietic stem cell transplant. Allogeneic transplantation is efficacious but is associated with high transplant-related mortality.

Undifferentiated malignant neoplasms of the sinonasal tract

CONTEXT

The most commonly encountered malignant neoplasms of the sinonasal tract are the keratinizing and nonkeratinizing types of squamous cell carcinoma. However, this complex anatomic region may represent the site of aggressive, non-squamous cell epithelial and nonepithelial malignant neoplasms of varying histogenesis, which are grouped under the term undifferentiated malignant neoplasms. Frequently, these undifferentiated malignancies share clinical and light microscopic features, which makes differentiation of one from the other virtually impossible without the use of adjunct analyses (eg, immunohistochemistry, electron microscopy, or molecular biologic studies). These tumors often are clinically aggressive and usually fatal, despite all attempts at controlling disease. Nevertheless, differentiating these tumors has clinical import because advances in therapeutic intervention may increase survival with good quality of life, and in some instances may achieve a cure.

OBJECTIVE

To compare and contrast the clinical, light microscopic, and immunohistochemical features of sinonasal undifferentiated malignant neoplasms.

DATA SOURCES

Case-derived material and literature review.

CONCLUSIONS

A variety of undifferentiated malignant neoplasms occur in the sinonasal tract with overlapping clinical and pathologic findings. In limited biopsy material, differentiation of these tumor types can be challenging. The pathologist plays a primary role in establishing the correct diagnosis, which often necessitates the use of adjunct studies that allow for differentiating among these neoplasms.

Uncommon cases of immature-type CD56+ natural killer (NK)-cell neoplasms, characterized by expression of myeloid antigen of blastic NK-cell lymphoma

Immature-type CD56(+) natural killer (NK)-cell neoplasms are classified as either myeloid/NK-cell precursor acute leukemia or blastic NK-cell lymphoma. We identified two cases of immature-type CD56(+) NK-cell neoplasms that were not categorizable as either of these entities. The first case involved a 74-year-old woman presenting with skin eruptions and pancytopenia due to bone marrow necrosis. Skin biopsy specimen revealed CD4(+), CD7(-), CD34(-), CD43(+), CD56(+), CD68(+), muramidase (lysozyme)(+), and myeloperoxidase (MPO)(-), and immunophenotyping of peripheral blood showed CD4(+), CD7(-), CD13(+), CD33(+), CD34(-), CD43(+), CD56(+), cytoplasmic (cy)CD68(+), CD123(+), and HLA-DR(+). The second case involved a 62-year-old man who had bilateral optic nerve tumor and presented with malignant cells in peripheral blood. Cell surface markers of malignant cells showed CD4(+), CD7(-), CD13(+), CD33(+), CD34(-), CD43(+), CD56(+), cyCD68(+), and HLA-DR(+). The phenotypes of tumor cells in both cases were compatible with blastic NK-cell lymphoma, except for the expression of myeloid antigen. Clinical presentations of these cases showed characteristics of both blastic NK-cell lymphoma and myeloid/NK-cell precursor acute leukemia.