The pathology of NK-cell lymphomas and leukemias

Recurrent GNAQ mutation encoding T96S in natural killer/T cell lymphoma

Natural killer/T cell lymphoma (NKTCL) is a rare and aggressive malignancy with a higher prevalence in Asia and South America. However, the molecular genetic mechanisms underlying NKTCL remain unclear. Here, we identify somatic mutations of GNAQ (encoding the T96S alteration of Gαq protein) in 8.7% (11/127) of NKTCL patients, through whole-exome/targeted deep sequencing. Using conditional knockout mice (Ncr1-Cre-Gnaqfl/fl), we demonstrate that Gαq deficiency leads to enhanced NK cell survival. We also find that Gαq suppresses tumor growth of NKTCL via inhibition of the AKT and MAPK signaling pathways. Moreover, the Gαq T96S mutant may act in a dominant negative manner to promote tumor growth in NKTCL. Clinically, patients with GNAQ T96S mutations have inferior survival. Taken together, we identify recurrent somatic GNAQ T96S mutations that may contribute to the pathogenesis of NKTCL. Our work thus has implications for refining our understanding of the genetic mechanisms of NKTCL and for the development of therapies.

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.

Comparison of Diagnostic Cytomorphology of Natural Killer/T-Cell Lymphoma (Nasal Type) in Conventional Smears, Liquid-Based Preparations, and Histopathology

Natural killer (NK)/T-cell lymphoma is formally referred to as extranodal NK/T-cell lymphoma, nasal type (ENKTCL), in the 2008 and 2016 World Health Organization (WHO) classifications. NK/T-cell lymphoma, nasal type, is a rare but clinically important lymphoid neoplasm. It is the predominant type of extranodal lymphoma associated with the Epstein–Barr virus (EBV). NK/T-cell lymphoma is marked by a wide cytomorphological spectrum. The cytological findings may be so subtle that NK/T-cell lymphoma could possibly be easily overlooked. Here, we report a case of NK/T-cell lymphoma involving the sinonasal region with lymph node involvement. Fine needle aspiration of the neck lymph node and punch biopsy of the nasal mucosa were performed. The diagnosis of NK/T-cell lymphoma was confirmed based on pathological and immunohistochemical analyses, as well as in situ hybridization for EBV-encoded mRNA (EBER). The present case report underlines the importance of prompt clinicopathological assessment in suspected cases. The comparison of cytomorphologic features of NK/T-cell lymphoma in various specimens is presented.

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.

Aggressive natural killer (NK)-cell leukaemia and extranodal NK/T-cell lymphoma are two distinct diseases that differ in their clinical presentation and cytogenetic findings

AIMS

Aggressive natural killer (NK)-cell leukaemia (ANKCL) and extranodal NK/T-cell lymphoma (ENKTCL) with secondary bone marrow involvement are rare bone marrow NK/T-cell neoplasms and share similar features. This study aimed to distinguish these two entities.

METHODS AND RESULTS

We studied bone marrow NK/T-cell neoplasms by classifying them into those with no extramedullary mass (group 1, eight cases) and those with extramedullary mass (group 2, 13 cases). The two groups showed similar clinical presentations and pathological features. Fever and cytopenia were the most common clinical presentations in both groups. The neoplastic cells varied from small and relatively monotonous cells to large pleomorphic cells. In six cases (two in group 1, and four in group 2), the neoplastic infiltrate was inconspicuous, consisting of ≤10% of marrow cells in the interstitium, which were hardly identified by haematoxylin and eosin staining alone. Nearly all patients rapidly died, regardless of the neoplastic infiltrate volume. All of the group 1 patients fulfilled the World Health Organisation 2017 diagnostic criteria of ANKCL, and their survival was significantly worse than that of the group 2 patients (P = 0.035). In addition, there was a significant association between being in group 1 and chromosome 7 abnormalities. Chromosome 6q deletion, which is commonly reported in ENKTCL, was seen in two of our group 2 patients, and was not observed in any of our group 1 patients.

CONCLUSION

ANKCL with no extramedullary mass should be distinguished from ENKTCL with bone marrow involvement, as the former shows distinct outcomes and genetic features.

NKL homeobox gene MSX1 acts like a tumor suppressor in NK-cell leukemia

NKL homeobox gene MSX1 is physiologically expressed in lymphoid progenitors and subsequently downregulated in developing T- and B-cells. In contrast, elevated expression levels of MSX1 persist in mature natural killer (NK)-cells, indicating a functional role in this compartment. While T-cell acute lymphoblastic leukemia (T-ALL) subsets exhibit aberrant overexpression of MSX1, we show here that in malignant NK-cells the level of MSX1 transcripts is aberrantly downregulated. Chromosomal deletions at 4p16 hosting the MSX1 locus have been described in NK-cell leukemia patients. However, NK-cell lines analyzed here showed normal MSX1 gene configurations, indicating that this aberration might be uncommon. To identify alternative MSX1 regulatory mechanisms we compared expression profiling data of primary normal NK-cells and malignant NK-cell lines. This procedure revealed several deregulated genes including overexpressed IRF4, MIR155HG and MIR17HG and downregulated AUTS2, EP300, GATA3 and HHEX. As shown recently, chromatin-modulator AUTS2 is overexpressed in T-ALL subsets where it mediates aberrant transcriptional activation of MSX1. Here, our data demonstrate that in malignant NK-cell lines AUTS2 performed MSX1 activation as well, but in accordance with downregulated MSX1 transcription therein we detected reduced AUTS2 expression, a small genomic deletion at 7q11 removing exons 3 and 4, and truncating mutations in exon 1. Moreover, genomic profiling and chromosomal analyses of NK-cell lines demonstrated amplification of IRF4 at 6p25 and deletion of PRDM1 at 6q21, highlighting their potential oncogenic impact. Functional analyses performed via knockdown or forced expression of these genes revealed regulatory network disturbances effecting downregulation of MSX1 which may underlie malignant development in NK-cells.

Clinicopathological analysis of 12 patients with Epstein-Barr virus-positive primary intestinal T/natural killer-cell lymphoma (EBV+ ITNKL)

AIMS

Epstein-Barr virus-positive (EBV⁺ ) intestinal T/natural killer (NK) cell lymphoma (ITNKL) is an uncommon tumour with an extremely aggressive clinical behaviour. However, the clinicopathological characteristics of this tumour, including T cell receptor (TCR) phenotype and the patient's background, remain unknown. The aim of this study was to elucidate the detailed clinicopathological profile of EBV⁺ ITNKL.

METHODS AND RESULTS

We enrolled 12 patients with EBV⁺ ITNKL without nasal involvement into the study. All patients were characterized by involvement of the small intestine with concurrent lesions of the large intestine in two patients. Seven patients (58%) had Lugano stages IIE/IV disease and eight (67%) were categorized as high-intermediate/high-risk according to the Prognostic Index for PTCL (PIT). Three patients (25%) with an age of onset of less than 50 years had chronic active EBV infection (CAEBV). Five CD56-positive patients (42%) had a poorer prognosis than those without CD56 expression (P = 0.008). NK cell-type lymphoma defined by the absence of any TCR expression or clonal TCR-γ rearrangement was found in six patients (50%). Interestingly, EBV⁺ intra-epithelial lymphocytosis was observed in one case with a background of CAEBV.

CONCLUSIONS

This study is the first to shed light on the significant heterogeneity of EBV⁺ ITNKL and its relationship with CAEBV, especially in patients younger than 50 years of age. These observations will provide a guide for diagnostic and therapeutic approaches in routine practice.

Uncommon Variants of T-Cell Lymphomas

Peripheral T-cell lymphomas represent 10% to 15% of non-Hodgkin lymphomas and comprise more than 20 different entities. Treatment of very rare T-cell lymphomas can be challenging because there are no large or randomized studies to guide clinical decision making, and treatment paradigms are often based on small series or imperfect data. Although a strict algorithm cannot be written with certainty, through the literature that exists and clinical experience, themes and principles of approaches do emerge that when coupled with clinical judgment allow reasonable and logical decisions.

Pancreas Metastasization of Nasal NK/T-Cell Lymphoma: A Case Report

We report here a case of nasal natural killer/T-cell lymphoma with metastasization into the pancreas. A 43-year-old Chinese female patient presented with right nasal obstruction and purulent rhinorrhea that lasted for the past half year and worsened gradually despite antibiotic medical treatment. Physical examination revealed a mass in the right nasal cavity and an enlarged lymph node in the right submandibular region. A PET/CT scan and immunostaining of the resectate led to a diagnosis of nasal natural killer/T-cell lymphoma, clinical stage IIE, and the International Prognostic Index score of 1. The patient received radiotherapy followed by four cycles of the CHOP chemotherapy. A complete remission was achieved, and the patient was disease-free for 9 months. On a subsequent follow-up, abdominal ultrasound scan, enhanced abdominal CT scan, and ultrasound-guided fine-needle aspiration biopsy revealed pancreatic metastasis secondary to nasal lymphoma. Radiotherapy (40 Gy) to the whole pancreas was done, followed by two courses of the SMILE regime chemotherapy, leading to a complete remission. At the moment, the patient is undergoing subsequent chemotherapy.

Uncommon non-Hodgkin lymphomas of childhood: pathological diagnosis, clinical features and treatment approaches

We provide a review of the pathological and clinical features for uncommon B-cell and T-cell lymphomas of childhood with a specific focus on advances in treatment approaches and outcomes. There is clearly a need for prospective investigation of both the clinical and biological features of the uncommon non-Hodgkin lymphoma subtypes in childhood. These results should lead to more uniform and more effective treatment approaches.

Pseudoepitheliomatous hyperplasia mimicking invasive squamous cell carcinoma in extranodal natural killer/T-cell lymphoma: a report of 34 cases

AIMS

Pseudoepitheliomatous hyperplasia (PEH) is defined as a pattern of epidermal reaction. However, it has not yet been extensively documented in extranodal natural killer/T-cell lymphoma (ENKTL). The aim of our study was to analyse a series of ENKTLs concomitant with PEH mimicking squamous cell carcinoma (SCC).

METHODS AND RESULTS

We analysed 34 cases of ENKTL with PEH. In our study, the incidence of PEH was 3.8% in ENKTLs diagnosed over a 13-year period. All 34 cases presented with PEH, appearing as tongue-like projections of squamous epithelium into the underlying submucosa/dermis with variable depths and jagged borders. The keratinocytes sometimes showed a minor degree of cytological atypia, mostly in the stratum basale, and keratinocyte necrosis was absent. Atypical mitoses and a high nuclear/cytoplasmic ratio were absent. The submucosa and the squamous cell cords were also permeated by atypical lymphocytes.

CONCLUSIONS

ENKTL can be associated with PEH, and the atypical lymphoid cell population can be highly subtle, and therefore may be easily mistaken for SCC, leading to inappropriate therapy. A correct diagnosis requires awareness and recognition of this pitfall by recognizing the associated conditions listed above, which distinguish PEH from SCC.

Paediatric cutaneous lymphomas: a review and comparison with adult counterparts

Primary cutaneous lymphomas (CL) in children is rare. Only a few studies focused specifically on paediatric CL and therefore little is known whether primary CL in children are similar to or different from their adult counterparts with respect to the clinicopathological presentation, behaviour and prognosis. An extensive literature search using PubMed/MEDLINE from January 1995 through July 2014 was undertaken for articles reporting cases of paediatric CL. In addition, we identified 31 children with CL in our institutions. Mycosis fungoides and lymphomatoid papulosis are the two most prevalent lymphoma forms in children. A few entities of cutaneous lymphomas such as cutaneous diffuse large B-cell lymphoma leg type, and Sézary syndrome have not been reported so far in children. Other lymphoma entities such as hydroa vacciniforme-like lymphoma are mostly seen in certain geographic areas (Asia, Central and South America). In the paediatric population, low-malignant indolent forms such as primary cutaneous marginal zone lymphoma and primary cutaneous follicle centre lymphoma are very rare, whereas the more aggressive forms of B-cell lymphomas, precursor lymphoblastic lymphomas, and blastic plasmacytoid dendritic cell neoplasm are the most common forms in children, mostly involving the skin secondarily. Most paediatric lymphomas have similar clinicopathological features and course as their adults counterparts, particularly in the group of cutaneous T-cell lymphomas. The spectrum of cutaneous B-cell lymphomas in children significantly differs from the one in adults. Diagnostic work-up and treatment of paediatric patients with lymphomas are best achieved in close collaboration with paediatric haematopathologists and oncologists.

Rare aggressive natural killer cell leukemia presented with bone marrow fibrosis - a diagnostic challenge

Aggressive natural killer cell leukemia is an extraordinary rare aggressive malignant neoplasm of natural killer cells. Although its first recognition as a specific entity was approximately 20 years ago, this leukemia has not yet been satisfactorily characterized as fewer than 200 cases have been reported in the literature and up to our knowledge, this is the first case report in Qatar. Reaching a diagnosis of aggressive natural killer leukemia was a challenging experience, because in addition to being a rare entity, the relative scarcity of circulating neoplastic cells, failure to obtain an adequate aspirate sample sufficient to perform flow cytometric analysis, together with the absence of applicable method to prove NK clonality (as it lack specific clonal marker); our case had atypical confusing presentation of striking increase in bone marrow fibrosis that was misleading and complicated the case further. The bone marrow fibrosis encountered may be related to the neoplastic natural killer cells' chemokine profile and it may raise the awareness for considering aggressive natural killer leukemia within the differential diagnosis of leukemia with heightened marrow fibrosis.

BamHI-A rightward frame 1, an Epstein-Barr virus-encoded oncogene and immune modulator

Epstein–Barr virus (EBV) causes several benign and malignant disorders of lymphoid and epithelial origin. EBV-related tumors display distinct patterns of viral latent gene expression, of which the BamHI-A rightward frame 1 (BARF1) is selectively expressed in carcinomas, regulated by cellular differentiation factors including ΔNp63α. BARF1 functions as a viral oncogene, immortalizing and transforming epithelial cells of different origin by acting as a mitogenic growth factor, inducing cyclin-D expression, and up-regulating antiapoptotic Bcl-2, stimulating host cell growth and survival. In addition, secreted hexameric BARF1 has immune evasive properties, functionally corrupting macrophage colony stimulating factor, as supported by recent functional and structural data. Therefore, BARF1, an intracellular and secreted protein, not only has multiple pathogenic functions but also can function as a target for immune responses. Deciphering the role of BARF1 in EBV biology will contribute to novel diagnostic and treatment options for EBV-driven carcinomas. Herein, we discuss recent insights on the regulation of BARF1 expression and aspects of structure-function relating to its oncogenic and immune suppressive properties. © 2013 The Authors. Reviews in Medical Virology published by John Wiley & Sons, Ltd.

Non-mycosis fungoides cutaneous T-cell lymphomas: report of the 2011 Society for Hematopathology/European Association for Haematopathology workshop

Primary cutaneous T-cell lymphomas (CTCL) excluding mycosis fungoides (MF) were discussed in 2 sessions of the 2011 Society for Hematopathology/ European Association of Haematopathology Workshop, Los Angeles, CA. Session 2 focused on primary cutaneous CD30+ T-cell lymphoproliferative disorders and their differential diagnosis, including systemic CD30+ T-cell lymphoma secondarily infiltrating the skin. Interesting features like special morphologic variants and atypical phenotypes were presented. In addition, the possibility of rare ALK+ primary cutaneous lymphomas was discussed. Session 3 examined other more uncommon non-MF CTCLs, including subcutaneous panniculitis-like T-cell lymphoma, extranodal NK/T-cell lymphoma, hydroa vacciniforme-like T-cell lymphoma, and rare subtypes of primary cutaneous peripheral T-cell lymphoma, not otherwise specified. In addition, systemic T-cell lymphomas involving the skin secondarily, such as angioimmunoblastic T-cell lymphoma, were included in this session. In this report, novel findings, areas of special interest, and diagnostic challenges emerging from the cases submitted to the workshop will be highlighted. The necessity to integrate histologic, immunophenotypical, genetic, and in particular, clinical data to arrive at the correct diagnosis, and subsequently provide adequate treatment, is emphasized.

Elevated serum granulysin and its clinical relevance in mature NK-cell neoplasms

Mature natural killer (NK)-cell neoplasms include extranodal NK/T cell lymphoma, nasal type (ENKL), aggressive NK-cell leukemia (ANKL) and chronic lymphoproliferative disorders of NK cells (CLPD-NK). Granulysin, a cytolytic granule protein, is expressed in cytotoxic T cells and NK cells, and is found in the sera as well, and functions as a cytotoxic and proinflammatory protein. Cytolytic proteins, such as granzyme B and perforin, have been shown to play crucial pathophysiological roles in NK/T cell neoplasms and have also been utilized for diagnostic purposes. Granulysin in NK-cell proliferative disorders, however, has yet to be fully analyzed. To elucidate the clinical relevance of granulysin in mature NK-cell neoplasms, we measured serum granulysin and analyzed cytolytic molecules immunohistologically. The median concentrations of serum granulysin were 39.0, 2.85, 2.8 and 1.35 ng/ml in ANKL, ENKL, CLPD-NK and healthy subjects, respectively (P < 0.01). Serum granulysin was significantly elevated in patients with ANKL compared with the levels in ENKL (P = 0.006) and CLPD-NK (P = 0.037). Furthermore, serum granulysin was correlated with whole-blood EBV viral load in ENKL and ANKL (P = 0.005) and was significantly reduced after treatment. Different expression patterns of cytolytic granule proteins were observed among the mature NK-cell neoplasms. Granulysin is closely associated with the characteristics of NK-cell neoplasms and serum granulysin may serve as a novel biomarker for these disorders.

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.

Clinicopathological analysis of the age-related differences in patients with Epstein-Barr virus (EBV)-associated extranasal natural killer (NK)/T-cell lymphoma with reference to the relationship with aggressive NK cell leukaemia and chronic active EBV infection-associated lymphoproliferative disorders

AIMS

Extranodal natural killer (NK)/T-cell lymphoma (NKTL), comprising nasal NKTL and extranasal NKTL (ENKTL), is associated with Epstein-Barr virus (EBV). A bimodal age distribution was noted in NKTL patients. We examined the clinicopathological differences between two age groups of ENKTL patients (n = 23) and compared the findings with those of aggressive NK cell leukaemia (ANKL; n = 10) and monoclonal chronic active EBV infection-associated T/NK-cell lymphoproliferative disorders [chronic active EBV infection/TNK-lymphoproliferative disorders (CAEBV/TNK-LPD)] of NK-cell type (n = 45).

METHODS AND RESULTS

Distinct differences existed between elderly (> 50 years; n = 13) and younger (≤ 50 years; n = 10) ENKTL patients; the latter showed a higher disease stage (P = 0.0286), worse performance status (P = 0.0244), more frequent B symptoms (P = 0.0286) and more frequent liver, spleen and bone marrow involvement (P = 0.0222, 0.0005 and 0.0259, respectively). Few clinicopathological differences existed between younger ENKTL and ANKL patients. Patients with monoclonal CAEBV/TNK-LPD of NK-cell type (n = 45) showed features similar to those in younger ENKTL/ANKL patients, except a more juvenile onset of CAEBV-related symptoms and better prognosis. However, the onset age of overt leukaemia/lymphoma in CAEBV/TNK-LPD patients and overall survival thereafter were similar to those in younger ENKTL/ANKL patients.

CONCLUSIONS

ENKTL (≤ 50 years) is distinct from that in elderly patients and may encompass ANKL and overlap in the clinicopathological profile with NK-cell type CAEBV/TNK-LPD.

Clinicopathological Features and Outcomes of T- and NK-Cell Lymphomas in European Russia

With the introduction of the revised World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissues in 2001, many patients had to be re-evaluated for the correct diagnosis of T- and NK-cell lymphomas. Because some T-cell malignancies are associated with poor outcome, it is important to identify subsets of patients that may benefit from novel or more intensive therapies. The purpose of this study was to determine, for the first time, the relative frequencies, pathological features and outcomes of patients with T- and NK-cell lymphomas in a predominantly Russian Slavic population. We identified 291 patients with a diagnosis of T- and NK-cell malignancies treated at our Center between 2000-2008. In applying the revised WHO classification, we confirmed the diagnosis and had complete clinical follow up and pathological information on 264 cases that were included in the analysis. We found some differences in frequency of several subsets as compared with previously published reports, including younger age of onset and relatively higher incidence of T-LGL in our patients. We also confirm that intensive treatment regimens of advanced stage PTCL and ALK—ALCL led to considerable improvement in response rates, but not in the overall survival.

Pathobiology of Epstein-Barr virus-driven peripheral T-cell lymphomas

In the present review, the authors described the pathobiological features of Epstein-Barr virus (EBV)-driven T/natural killer cell-derived malignancies. These rare tumors appear to be quite heterogeneous with regard to both clinical and pathologic features. Nonetheless, some elements, especially regarding the possible role of EBV (ie, genomic predisposition, pathogenesis, pattern of latency), are similar, enforcing the concept of a causative role for the virus. In clinical practice, although definitely rare in Western countries, the tumors are not exceptional; thus, they should be taken into account in the differential diagnosis of T-lymphoproliferative disorders, also considering the need for extremely prompt intervention. The prognosis of such tumors is generally poor using current approaches. A better understanding of their molecular pathogenesis may lead to significant therapeutic improvements. For example, the nuclear factor-KB pathway and platelet-derived growth factor receptor inhibition may represent 2 options to be tested in clinical trials.

Deciphering the role of Epstein-Barr virus in the pathogenesis of T and NK cell lymphoproliferations

Epstein-Barr virus (EBV) is a highly successful herpesvirus, colonizing more than 90% of the adult human population worldwide, although it is also associated with various malignant diseases. Primary infection is usually clinically silent, and subsequent establishment of latency in the memory B lymphocyte compartment allows persistence of the virus in the infected host for life. EBV is so markedly B-lymphotropic when exposed to human lymphocytes in vitro that the association of EBV with rare but distinct types of T and NK cell lymphoproliferations was quite unexpected. Whilst relatively rare, these EBV-associated T and NK lymphoproliferations can be therapeutically challenging and prognosis for the majority of patients is dismal. In this review, we summarize the current knowledge on the role of EBV in the pathogenesis of these tumours, and the implications for treatment.

Automatic classification of lymphoma images with transform-based global features

We propose a report on automatic classification of three common types of malignant lymphoma: chronic lymphocytic leukemia, follicular lymphoma, and mantle cell lymphoma. The goal was to find patterns indicative of lymphoma malignancies and allowing classifying these malignancies by type. We used a computer vision approach for quantitative characterization of image content. A unique two-stage approach was employed in this study. At the outer level, raw pixels were transformed with a set of transforms into spectral planes. Simple (Fourier, Chebyshev, and wavelets) and compound transforms (Chebyshev of Fourier and wavelets of Fourier) were computed. Raw pixels and spectral planes were then routed to the second stage (the inner level). At the inner level, the set of multipurpose global features was computed on each spectral plane by the same feature bank. All computed features were fused into a single feature vector. The specimens were stained with hematoxylin (H) and eosin (E) stains. Several color spaces were used: RGB, gray, CIE-L*a*b*, and also the specific stain-attributed H&E space, and experiments on image classification were carried out for these sets. The best signal (98%-99% on earlier unseen images) was found for the HE, H, and E channels of the H&E data set.

NK cell lymphoma, nasal type, with massive lung involvement: a case report

Extranodal NK/T cell lymphoma, nasal type, is an Epstein-Barr virus-associated lymphoma that most commonly involves the nasal cavity and upper respiratory tract. Lung involvement by NK/T cell lymphoma is rare and seldom reported in the literature. We describe the unusual case of a 41-year-old male with NK cell lymphoma, nasal type, who presented with massive secondary lung involvement 2.5 years after the detection of a retroperitoneal mass. The diagnosis was made by open lung biopsy. Despite aggressive treatment, the patient died shortly after the initiation of therapy. Lung involvement by NK/T cell lymphoma occurs most commonly as part of widely disseminated disease and carries a poor prognosis for the patient. Novel agents and innovative therapies need to be developed for this aggressive lymphoma.

[A case of CD56+ extranodal NK/T-cell lymphoma, nasal type, presenting as a duodenal ulcer bleeding]

Extranodal NK/T-cell lymphoma is a recently recognized distinct entity within the World Health Organization classification of lymphoid tumors. It is relatively prevalent in Asian and South American populations. It most commonly occurs in the nasal or paranasal areas and less frequently in the skin, the soft tissue, and the gastrointestinal tract. Among these, extranodal NK/T-cell lymphoma of the gastrointestinal tract has shown an aggressive clinical course. We report a case of CD56+ extranodal NK/T-cell lymphoma presenting as a duodenal ulcer bleeding. A 62-year-old male patient presented with melena and abdominal pain. Endoscopic examination of the upper gastrointestinal tract showed the duodenal ulcer covered by blood clot. Pathologic examination revealed the diffuse infiltration of atypical lymphocytes with an angiocentric growth pattern, which was positive for CD3, CD56, and granzyme. The patient showed rapid deteriorating clinical course and died on day 14 after admission. Thus, we report this case with the review of literatures.

NF-kappaB activation through the alternative pathway correlates with chemoresistance and poor survival in extranodal NK/T-cell lymphoma, nasal type

OBJECTIVE

Nuclear factor-kappaB (NF-kappaB) activation has been identified in a variety of solid tumors and lymphoid malignancies. The aim of our study was to determine the expression status and clinical significance of NF-kappaB in extranodal natural killer (NK)/T-cell lymphoma, nasal type.

METHODS

Tumor specimens from 23 patients with previously untreated NK/T-cell lymphoma initially treated with cyclophosphamide, vincristine, doxorubicin and prednisone (CHOP) or CHOP-based chemotherapy were examined by immunohistochemistry for three NF-kappaB subunits (p65, p50 and p52), which are involved in either the canonical or alternative pathway.

RESULTS

None of the cases could be detected with p65 or p50 nuclear staining. On the other hand, 15 (65.2%) cases had p52 nuclear staining, suggesting NF-kappaB activation through the alternative pathway. All major clinical characteristics were balanced between NF-kappaB p52-positive and -negative patients. The objective response rate achieved in NF-kappaB-positive patients was significantly lower than that in negative patients (33.3% vs. 87.5%, P = 0.027). At a median follow-up of 25 months, 8 (53.3%) of 15 NF-kappaB-positive patients had died compared with none of 8 NF-kappaB-negative patients (P = 0.041). In a multivariate analysis, NF-kappaB status and stage were identified to be independent prognostic factors.

CONCLUSIONS

Our results suggest that NF-kappaB activation through the alternative pathway is frequently observed in NK/T-cell lymphoma and associated with chemoresistance and poor survival.

Genomic analyses reveal global functional alterations that promote tumor growth and novel tumor suppressor genes in natural killer-cell malignancies

Natural killer (NK)-cell malignancies are among the most aggressive lymphoid neoplasms with very poor prognosis. We performed array comparative genomic hybridization analysis on a number of NK cell lines and primary tumors to gain better understanding of the pathogenesis and tumor biology of these malignancies. We also obtained transcriptional profiles of genes residing in these regions and compared them with normal and activated NK cells. Only 30-50% of the genes residing in the gained or deleted regions showed corresponding increased or decreased expression. However, many of the upregulated genes in regions of gain are functionally important for the proliferation and growth of the neoplastic population. Genes downregulated in regions of loss included many transcription factors or repressors, tumor suppressors or negative regulators of the cell cycle. The minimal common region of deletion in 6q21 included three known genes (PRDM1, ATG5 and AIM1) showing generally low expression. Mutations resulting in truncated PRDM1 and changes in conserved amino-acid sequences of AIM1 were detected. Highly methylated CpG islands 5' of PRDM1 and AIM1 correlated with low expression of the transcripts. Reversal of methylation by Decitabine induced expression of PRDM1 and cell death. In conclusion, we have shown a general tumor-promoting effect of genetic alterations and have identified PRDM1 as the most likely target gene in del6q21. ATG5, an essential gene for autophagy and AIM1, a gene implicated in melanoma, may also participate in the functional abnormalities.

Epstein-Barr virus in lymphoproliferative processes: an update for the diagnostic pathologist

The Epstein-Barr virus is an orally transmitted herpesvirus that is widespread in human populations and exhibits marked B-cell tropism. It is associated with more human neoplasms than any other known virus, and its role in the pathogenesis of such neoplasms has been the subject of intense investigation. This review presents an overview and update of the biology of Epstein-Barr virus and the diagnostic features of lymphoproliferative disorders associated with this intriguing human pathogen.

An Epstein-Barr virus positive natural killer lymphoma xenograft derived for drug testing

Natural killer (NK) lymphomas occurring more frequently in the Far East and South America respond poorly to anthracycline-based regimens. Here we report an in vivo NK lymphoma xenograft (NK-S1) derived from the testicular metastasis of a patient with an extranodal NK lymphoma (nasal type). The NK-S1 xenograft, established in severe combined immune deficient (SCID) mice retained the same imunophenotypic features as the original tumor. NK-S1 disseminated intra-abdominally to the testis, intestine and liver. Although doxorubicin, rapamycin, bevacizumab, rapamycin-doxorubicin, and bevacizumab-doxorubicin had no effects on the growth of subcutaneous NK-S1 xenografts, intraperitoneal (IP) delivery of cyclophosphamide caused complete tumor regression; this tumor regression was associated with apoptosis, upregulation of activated caspase-3, and cleaved Poly(ADP-ribose) polymerase (PARP). In an IP model of NK lymphoma, cyclophosphamide also prolonged the survival of mice and potently inhibited tumor dissemination and ascites formation. Our data suggest that the NK-S1 xenograft is a useful tool for screening preclinical drugs, and cyclophosphamide may be a useful drug for the treatment of this disease.

Expression of the metalloproteases MMP-1, MMP-2, MMP-3, MMP-9, MMP-11, TIMP-1 and TIMP-2 in angiocentric midfacial lymphomas

Background

Extranodal T/NK cell lymphomas possess distinctive clinico-pathological characteristics: they are angiocentric, exhibit extensive necrosis. Prognosis is poor in the short term. The objective is to explore the expression of different MMPs in the cells and stroma which are around of the blood vessels damaged and their correlation with clinico-pathological parameters.

Patients and methods

Twenty cases of this type of lymphomas were studied and collected patient clinical data. The expressions of MMP-1, 2, 3, 9, 11, 13 and TIMP-1, 2 were studied by immunohistochemistry. Ultrastructural studies were performed in two cases. Statistical analysis was done with Fisher's exact test, Chi² test.

Results

Of the 20 patients, 13 were men with median age of 43 years. In 13 patients the primary tumor was localized in the nasal cavity. Treatment was combined chemotherapy and radiotherapy in 60%. The 55% advanced clinical stages, 70% died from the disease. There were neoplastic cell and peritumoral fibroblasts positivity to MMP-1 and MMP-11 in most of the cases. The MMPs-2, 3 and 9 were expressed in neoplastic cell between 30 to 65%of the cases. TIMP-1 was presented mainly in the epithelium and TIMP-2 was poor expressed of the all cases.

Conclusion

There were no statistical significance between the different enzymes used and the clinical parameters, besides status and survival of the patients. It is necessary to study more enzymes and focus them to quantify and determine their activity, in order to have a better correlation with histological features in this type of neoplasm.

Incidence of TCR and TCL1 gene translocations and isochromosome 7q in peripheral T-cell lymphomas using fluorescence in situ hybridization

Translocations involving the T-cell receptor (TCR) and TCL1 genes occur in T-cell precursor lymphoblastic leukemia/lymphoma and prolymphocytic leukemia; isochromosome 7q has been associated with hepatosplenic T-cell lymphoma. However, the incidence of these abnormalities in peripheral T-cell lymphomas (PTCLs) as a whole has not been well defined. We studied genetic abnormalities in 124 PTCLs seen at the Mayo Clinic, Rochester, MN, between 1987 and 2007. Tissue microarrays were screened using 2-color break-apart fluorescence in situ hybridization probes flanking the TCRalpha (TCRA, 14q11), TCRbeta (TCRB, 7q35), and TCRgamma (TCRG, 7p15) genes and the TCL1 gene (14q32). Isochromosome 7q was analyzed by using a 2-color probe to 7p and 7q32.1. Translocations involved TCRA in 3 (2.9%) of 102 cases and TCRB in 1 (1%) of 88. Isochromosome 7q was detected in 2 cases of extranodal NK/T-cell lymphoma, nasal type, and 2 cases of anaplastic lymphoma kinase-negative anaplastic large cell lymphoma. One of the latter cases also had a translocation of TCRA, and further studies confirmed a novel t(5;14) translocation.

Angiocentric lesions of the head and neck

Angiocentric lesions of the head and neck encompass a variety of benign and malignant lesions. Not unexpectedly the sequelae of an angiocentric process independent of its benign or malignant nature is one of tissue ischemia with a potential for either breakdown or reparative fibrosis. Therefore, the clinical presentations can be very similar despite a varied pathogenesis. Among the benign reactive infiltrates that will be considered are angiocentric eosinophilic fibrosis, Wegener's granulomatosis, microscopic polyangiitis and cocaine associated mid line facial destruction. We will discuss other conditions which enter into the differential diagnosis either clinically or histologically including Erdheim Chester disease and mid line facial undermining unrelated to an angiocentric event specifically in the context of trigeminal trophic ulcer and relapsing polychondritis. The two main neoplastic conditions exhibiting angiocentricity are in the context of lymphomatoid granulomatosis and NK/T cell lymphoma; hence these two particular hematologic dyscrasias will be discussed in some detail in this review.

A Case of Aggressive NK/T-cell Lymphoma/Leukemia with Cutaneous Involvement in Adolescence

NK/T-cell lymphoma (NKTCL) is characterized by the expression of the NK-cell antigen CD56. Non-nasal NK/T-cell lymphomas are subdivided into primary cutaneous and 4 subtypes of secondary cutaneous lymphomas; nasal type, aggressive, blastic (blastoid), and other specific NK-like cell lymphoma. Aggressive NK/T-cell lymphoma/leukemia is a rare leukemic variant of nasal type NKTCL. We herein report a rare case of aggressive NK/T-cell lymphoma/leukemia with cutaneous involvement in adolescence.

NK-cell intravascular lymphomatosis--a mini-review

The majority of cases of intravascular lymphomatosis (IVL) is derived from B cells. However, IVL may also arise from T cells, or more rarely NK cells. The clinicopathological findings in six cases of NK-cell IVL (NK-IVL), including one new case, were summarised and compared with B-cell IVL (B-IVL) and T-cell IVL (T-IVL). Earlier onset of disease and female predominance were found in NK-IVL. NK-IVL was typically Epstein-Barr virus (EBV)-positive, whereas EBV was rarely detected in B-IVL. Cutaneous manifestations were common in NK-IVL with constant EBV infection. B-IVL showed a more favourable prognosis than T- or NK-IVL. Irrespective of immunophenotype, however, IVL showed a less favourable prognosis than ordinary lymphomas within the same immunophenotype. In summary, IVL of the B-, T- and NK-cell phenotypes is clinicopathologically distinct and shows similarities to their more common counterparts, i.e. diffuse large B-cell lymphoma, peripheral T-cell lymphoma, unspecified and extranodal NK/T-cell lymphoma, nasal type.

Acute leukemia immunohistochemistry: a systematic diagnostic approach

CONTEXT

The diagnosis and classification of leukemia is becoming increasingly complex. Current classification schemes incorporate morphologic features, immunophenotype, molecular genetics, and clinical data to specifically categorize leukemias into various subtypes. Although sophisticated methodologies are frequently used to detect characteristic features conferring diagnostic, prognostic, or therapeutic implications, a thorough microscopic examination remains essential to the pathologic evaluation. Detailed blast immunophenotyping can be performed with lineage- and maturation-specific markers. Although no one marker is pathognomonic for one malignancy, a well-chosen panel of antibodies can efficiently aid the diagnosis and classification of acute leukemias.

OBJECTIVE

To review important developments from recent and historical literature. General immunohistochemical staining patterns of the most commonly encountered lymphoid and myeloid leukemias are emphasized. The goal is to discuss the immunostaining of acute leukemias when flow cytometry and genetic studies are not available.

DATA SOURCES

A comprehensive review was performed of the relevant literature indexed in PubMed (National Library of Medicine) and referenced medical texts. Additional references were identified in the reviewed manuscripts.

CONCLUSIONS

Immunophenotyping of blasts using an immunohistochemical approach to lymphoid and myeloid malignancies is presented. Initial and subsequent additional antibody panels are suggested to confirm or exclude each possibility in the differential diagnosis and a general strategy for diagnostic evaluation is discussed. Although the use of immunohistochemistry alone is limited and evaluation by flow cytometry and genetic studies is highly recommended, unavoidable situations requiring analysis of formalin-fixed tissue specimens arise. When performed in an optimized laboratory and combined with a careful morphologic examination, the immunohistochemical approach represents a useful laboratory tool for classifying various leukemias.

Aggressive natural killer cell leukemia presenting with hemophagocytic lymphohistiocytosis

Aggressive natural killer cell leukemia (ANKL) is a very rare condition and when reported occurs almost exclusively in adults. We report a pediatric case of ANKL that presented with hemophagocytic syndrome, preceding the onset of leukemia by 12 weeks. Clinical and laboratory findings are discussed, along with morphology, immunophenotyping and cytogenetics, as well as the association with Epstein-Barr virus (EBV). This case is noteworthy for the expression of CD8 on the malignant cells, the cytogenetic findings that include abnormalities of chromosomes 6 and 7, as well as the age of the patient.

CD4+/CD56+ hematodermic neoplasm: presentation of 2 cases and review of the concept of an uncommon tumor originated in plasmacytoid dendritic cells expressing CD123 (IL-3 receptor alpha)

CD4/CD56 hematodermic neoplasm is a rare neoplasm presenting with cutaneous nodules, lymphadenopathy, bone marrow infiltration, and an aggressive clinical course. Recently, the plasmacytoid dendritic cell origin of this neoplasm has been demonstrated. Plasmacytoid dendritic cell is a hematopoietic-derived cell implicated in the regulation of innate and adaptive cell immunity and in the production of certain regulatory cytokines. Recently it has been demonstrated that these cells express cell surface markers such as IL-3 receptor alpha (CD123). In the present report, we describe the clinical, histologic, and immunohistochemical characteristics of 2 cases of CD4/CD56 hematodermic neoplasm. Both patients were male and the age at the time of diagnosis was 36 and 75 years, respectively. Clinical findings were limited to the skin and consisted of multiple cutaneous nodules located in the thorax and extremities, some of them ulcerated. Histologically, the tumors were characterized by a nonepidermotropic, dermal and subdermal infiltration of homogeneous medium-sized cells resembling lymphoblasts or myeloblasts. Immunohistochemical characterization of the tumors showed expression of CD4, CD56, CD43, and CD123, whereas CD8, CD20, and MPO were negative. Immunoreactivity for CD3, which has been described in rare occasions, was found only in one of the cases. This characteristic profile in addition to the expression of CD123, which was detected in both cases, can be used as valuable tools in the diagnosis of this rare neoplasm.

Epstein-Barr virus infection and risk of lymphoma: immunoblot analysis of antibody responses against EBV-related proteins in a large series of lymphoma subjects and matched controls

Epstein-Barr Virus (EBV) is consistently associated with distinct lymphoproliferative malignancies and aberrant EBV antibody patterns are found in most EBV cancer patients. We evaluate the detection of an abnormal reactive serological pattern to EBV (ab_EBV) infection and the risk of lymphoma in a multicentric case-control study. Serum samples were collected at study entry from 1,085 incident lymphoma cases from Spain, France, Germany, Czech Republic, Italy and 1,153 age, sex and country matched controls. EBV immunoglobulin G (IgG) serostatus was evaluated through a peptide-based ELISA combining immunodominant epitopes of EBNA1 (BKRF1) and VCA-p18 (BFRF3). Further, immunoblot analysis was performed to evaluate distinct antibody diversity patterns to EBV early antigens (EA), besides EBNA1, VCA-p18, VCA-p40 (BdRF1) and Zebra (BZLF1). Patients with chronic active EBV infection and aberrant EBV activity were characterized as having an abnormal reactive pattern (ab_EBV). Ab_EBV was observed in 20.9% of 2,238 included subjects with an increased proportion of cases presenting ab_EBV as compared to the control population (23.9% vs. 18.0% p = 0.001). Ab_EBV positivity was a risk factor for all lymphomas combined (odds ratio [OR] = 1.42, 95% confidence interval [CI]=1.15-1.74), and specifically for chronic lymphocytic leukaemia (OR = 2.96, 95%CI = 2.22-3.95). Lower levels of ab_EBV were observed for follicular lymphoma (OR = 0.38, 95%CI = 0.15-0.98). EBV may be involved in a larger subset of lymphomas among clinically immunocompetent subjects than previously thought, probably explained by an underlying loss of immune control of EBV latent infection. Ab_EBV is a useful tool to explore EBV imbalances preceding or paralleling possible EBV associated oncogenic events.

Progress in understanding and managing natural killer-cell malignancies

The World Health Organization classification of haematolymphoid tumours recognizes three categories of natural killer (NK)-cell neoplasms: blastic NK-cell lymphoma, aggressive NK-cell leukaemia, and extranodal NK/T-cell lymphoma, nasal-type. Recent studies indicate that CD4+CD56+ blastic NK-cell lymphoma is of plasmacytoid dendritic cell origin, and true tumours of precursor NK-cell origin may be present mainly in the CD4-CD56+ subset. Myeloid/NK-cell precursor acute leukaemia may also develop from precursor NK cells. However, because the developmental pathway of normal NK cells is not well understood, tumours of precursor NK-cell origin are not clearly identified. Among mature NK-cell tumours, extranodal NK/T-cell lymphoma is relatively common in Asia and Latin America. In localized disease, chemoradiotherapy seems to be promising, and in advanced disease, new combination chemotherapies are under active investigation. Aggressive NK-cell leukaemia is rare and has a poor prognosis. Because NK-cell neoplasms are rare and difficult to manage, rigorous studies are required for their understanding and management.