Type II EATL (epitheliotropic intestinal T-cell lymphoma): a neoplasm of intra-epithelial T-cells with predominant CD8αα phenotype

Intestinal T-cell lymphomas NOS presenting as a polypoidal lesion: A case report

RATIONALE

Intestinal T-cell lymphomas are exceedingly rare diseases. Intestinal T-cell lymphoma NOS, as a "wastebasket" category, is difficult to diagnosis. Endoscopy can identify abnormal mucosa in most patients at a reasonably early stage. Therefore, it is crucial to increase the understanding of endoscopists in terms of the endoscopic characteristics of ITCL.

PATIENT CONCERNS

A 74-year-old male alone with wasting as the major complaint, had multiple polypoid lesions in the large intestine. The patient then had endoscopic care.

DIAGNOSES

Only 1 polypoid lesion on white-light endoscopy in the sigmoid colon was pathologically diagnosed as intestinal T-cell lymphomas, not otherwise specified (ITCL-NOS).

INTERVENTIONS

The patient underwent intensity-reduced CHOP therapy.

OUTCOMES

The patient is still with controlled disease but developed chemotherapy-related side effects.

LESSONS

In the individual with unexplained anemia and waste, endoscopy should not be delayed. For each of polypoid lesion on white-light endoscopy, the endoscopist need to remain cautious, because every lesion in the same patient can exhibit the independence of histopathological features. Meanwhile, we suggest that endoscopists should routinely observe the terminal ileum, even take biopsy samples if necessary.

Cytogenetics in the management of mature T-cell and NK-cell neoplasms: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Mature T-cell and natural killer (NK)-cell neoplasms (MTNKNs) are a highly heterogeneous group of lymphomas that represent 10-15 % of lymphoid neoplasms and have usually an aggressive behavior. Diagnosis can be challenging due to their overlapping clinical, histological and immunophenotypic features. Genetic data are not a routine component of the diagnostic algorithm for most MTNKNs. Indeed, unlike B-cell lymphomas, the genomic landscape of MTNKNs is not fully understood. Only few characteristic rearrangements can be easily identified with conventional cytogenetic methods and are an integral part of the diagnostic criteria, for instance the t(14;14)/inv(14) or t(X;14) abnormality harbored by 95 % of patients with T-cell prolymphocytic leukemia, or the ALK gene translocation observed in some forms of anaplastic large cell lymphoma. However, advances in molecular and cytogenetic techniques have brought new insights into MTNKN pathogenesis. Several recurrent genetic alterations have been identified, such as chromosomal losses involving tumor suppressor genes (SETD2, CDKN2A, TP53) and gains involving oncogenes (MYC), activating mutations in signaling pathways (JAK-STAT, RAS), and epigenetic dysregulation, that have improved our understanding of these pathologies. This work provides an overview of the cytogenetics knowledge in MTNKNs in the context of the new World Health Organization classification and the International Consensus Classification of hematolymphoid tumors. It describes key genetic alterations and their clinical implications. It also proposes recommendations on cytogenetic methods for MTNKN diagnosis.

Clinical and Histopathological Features of an Italian Monocentric Series of Primary Small Bowel T-Cell Lymphomas

The gastrointestinal (GI) tract is the most common extranodal site of occurrence of non-Hodgkin lymphomas. Most GI lymphomas are of B-cell lineage, while T-cell lymphomas are less frequent. The aim of our retrospective study was to depict the clinical-pathological profile of a series of patients affected by intestinal T-cell lymphomas (ITCL) and possibly define hallmarks of these neoplasms. A total of 28 patients were included: 17 enteropathy-associated T-cell lymphomas (EATL), 5 monomorphic epitheliotropic T-cell lymphomas (MEITL), 3 indolent T-cell lymphoproliferative disorders of the gastrointestinal tract (ITCLDGT), and 3 intestinal T-cell lymphomas not otherwise specified (ITCL-NOS). Celiac disease (CD) was diagnosed in around 70% of cases. Diagnosis of EATL showed a significant correlation with CD30 expression, whereas MEITL with angiotropism and CD56 positivity. ITCLDGT cases showed plasma cells infiltration. Peripheral lymphocytosis, the absence of a previous diagnosis of CD, an advanced Lugano clinical stage, and the histological subtype ITCL-NOS were significantly associated with worse survival at multivariate analysis. Our findings about the epidemiological, clinical, and histopathological features of ITCL were in line with the current knowledge. Reliable prognostic tools for these neoplasms are still lacking but according to our results lymphocytosis, diagnosis of CD, Lugano clinical stage, and histological subtype should be considered for patient stratification.

ACVIM consensus statement guidelines on diagnosing and distinguishing low-grade neoplastic from inflammatory lymphocytic chronic enteropathies in cats

BACKGROUND

Lymphoplasmacytic enteritis (LPE) and low-grade intestinal T cell lymphoma (LGITL) are common diseases in older cats, but their diagnosis and differentiation remain challenging.

OBJECTIVES

To summarize the current literature on etiopathogenesis and diagnosis of LPE and LGITL in cats and provide guidance on the differentiation between LPE and LGITL in cats. To provide statements established using evidence-based approaches or where such evidence is lacking, statements based on consensus of experts in the field.

ANIMALS

None.

METHODS

A panel of 6 experts in the field (2 internists, 1 radiologist, 1 anatomic pathologist, 1 clonality expert, 1 oncologist) with the support of a human medical immunologist, was formed to assess and summarize evidence in the peer-reviewed literature and complement it with consensus recommendations.

RESULTS

Despite increasing interest on the topic for clinicians and pathologists, few prospective studies were available, and interpretation of the pertinent literature often was challenging because of the heterogeneity of the cases. Most recommendations by the panel were supported by a moderate or low level of evidence. Several understudied areas were identified, including cellular markers using immunohistochemistry, genomics, and transcriptomic studies.

CONCLUSIONS AND CLINICAL IMPORTANCE

To date, no single diagnostic criterion or known biomarker reliably differentiates inflammatory lesions from neoplastic lymphoproliferations in the intestinal tract of cats and a diagnosis currently is established by integrating all available clinical and diagnostic data. Histopathology remains the mainstay to better differentiate LPE from LGITL in cats with chronic enteropathy.

Spatially Guided and Single Cell Tools to Map the Microenvironment in Cutaneous T-Cell Lymphoma

Mycosis fungoides (MF) and Sézary syndrome (SS) are two closely related clinical variants of cutaneous T-cell lymphomas (CTCL). Previously demonstrated large patient-to-patient and intra-patient disease heterogeneity underpins the importance of personalized medicine in CTCL. Advanced stages of CTCL are characterized by dismal prognosis, and the early identification of patients who will progress remains a clinical unmet need. While the exact molecular events underlying disease progression are poorly resolved, the tumor microenvironment (TME) has emerged as an important driver. In particular, the Th1-to-Th2 shift in the immune response is now commonly identified across advanced-stage CTCL patients. Herein, we summarize the role of the TME in CTCL evolution and the latest studies in deciphering inter- and intra-patient heterogeneity. We introduce spatially resolved omics as a promising technology to advance immune-oncology efforts in CTCL. We propose the combined implementation of spatially guided and single-cell omics technologies in paired skin and blood samples. Such an approach will mediate in-depth profiling of phenotypic and molecular changes in reactive immune subpopulations and malignant T cells preceding the Th1-to-Th2 shift and reveal mechanisms underlying disease progression from skin-limited to systemic disease that collectively will lead to the discovery of novel biomarkers to improve patient prognostication and the design of personalized treatment strategies.

Difficulties in diagnosing intestinal T-cell lymphoma. Case report

The article describes a rare diagnosis of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), due to its veiled by a number of so-called masks of enteropathies. A detailed analysis of all clinical, morphological and immunohistochemical data made it possible to establish the correct diagnosis. The revealed pathology is extremely rare in practice, even among specialists in hematology. The article demonstrates the main stages of both a complex diagnosis and an attempt at therapy for this aggressive form of intestinal lymphoma.

Extranodal T- and NK-cell lymphomas

Non-cutaneous extranodal NK/T cell lymphoproliferations constitute a heterogenous group of rare neoplasms, occurring primarily in the gastro-intestinal tract, nasal area, spleen, and liver. Their nomenclature refers to their usual clinical presentation and predilection for specific anatomic sites-i.e. extranodal NK/T-cell lymphoma, nasal-type, hepatosplenic T-cell lymphoma, primary intestinal T-cell lymphomas, indolent lymphoproliferative disorders of the gastrointestinal tract, and breast implant-associated anaplastic large cell lymphoma. Extranodal tissues may also be involved by T-cell leukemias, or other entities usually presenting as nodal diseases. Primary extranodal entities range from indolent to highly aggressive diseases. Here, we will review the clinicopathologic features of the pertinent entities including the recent advances in their molecular and genetic characterization, with an emphasis on the changes introduced in the 2022 International Consensus Classification of lymphoid neoplasms, and highlight the diagnostic criteria helpful to sort out the distinction with potential mimickers.

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

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

The spectrum of intestinal mature T- and NK-cell neoplasms in a tertiary center in Taiwan with a high frequency of perforation

Primary intestinal T-cell lymphomas (PITLs) comprise enteropathy-associated T-cell lymphoma (EATL), monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), extranodal NK/T-cell lymphoma (ENKTL), anaplastic large cell lymphoma (ALCL), and intestinal T cell lymphoma, NOS (ITCL-NOS). MEITL is composed of monomorphic medium cells expressing CD8 and CD56, with a cytotoxic phenotype. We retrospectively analyzed 77 cases of intestinal T-cell lymphomas, 71 primary and six secondary, at a tertiary center in Taiwan from 2001 to 2021. Perforation occurred in 57 (74%) patients, including 56 (73%) at presentation and one after chemotherapy. The primary cases included MEITL (68%), ENKTL (14%), ITCL-NOS (13%), ALCL (4%), and EATL (1%). The perforation rate was 90%, 70%, and 22% in MEITL, ENKTL, and ITCL-NOS cases, respectively (p < 0.0001, Fisher's exact test). Most (75%; n = 36) MEITL cases were typical; while seven (15%) had atypical morphology and five (10%) exhibited atypical immunophenotype. The tumor cells of ITCL-NOS were pleomorphic, with various expression of CD8 or CD56. All METIL, ITCL-NOS and ALCL cases were negative for EBER; while all ENKTL cases, either primary or secondary, were positive for cytotoxic granules and EBER. The prognosis of PITL was poor, with a medium survival of 7.0, 3.3, and 3.7 months among patients with MEITL, ENKTL, and ITCL-NOS, respectively. Of the six secondary cases, the primary tumors orginated from nasal ENKTL (n = 5) and cutaneous PTCL-NOS (n = 1). We showed a wide spectrum of intestinal T-cell lymphomas in Taiwan, with MEITL as the most common PITL, a high rate of perforation, and a wider morphological and immunophenotypic spectrum.

Proteomics and genomics of a monomorphic epitheliotropic intestinal T-cell lymphoma: An extremely rare case report and short review of literature

RATIONALE

Monomorphic epitheliotropic intestinal T-cell lymphoma, formerly known as enteropathy-associated T-cell lymphoma, is an extremely rare, aggressive peripheral extranodal T-cell lymphoma, that is infrequent in native European and Caucasian populations. The current study presents the clinicopathological features, diagnostic approach, and clinical outcomes of this rare entity of lymphoma and highlights the importance of the early diagnosis of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL).

PATIENT CONCERNS

Main symptoms and/or important clinical findings: We present the case of a 69-year-old male patient presenting with an abdominal mass, intestinal transit disorder, and weight loss. The abdominal computed tomography (CT) revealed features suggestive of a malignancy. Following clinical and imaging investigations, surgical resection of the small intestine with other areas of involvement has been performed and further to the histopathological examination and immunohistochemical testing are mandatory.

DIAGNOSES AND INTERVENTIONS

Histopathological evaluation of the tumor revealed a proliferation of medium- to large-sized monomorphic lymphocytes, with vesicular nuclei, prominent nucleoli, and a moderate amount of clear to pale eosinophilic cytoplasm, with an association of infrequent Reed-Sternberg-like cells. Immunohistochemical assessment of the aforementioned tumor using CD3, CD8, CD5, CD20, and CD30 confirmed the T cell proliferation line and the monomorphic epitheliotropic intestinal T-cell lymphoma diagnosis.

LESSONS

The current report highlights the importance of early diagnosis of MEITL owing to its poor prognosis and presents histopathological features that help distinguish MEITL from inflammatory bowel diseases and less aggressive T-cell lymphomas.

Surgical management of monomorphic epitheliotropic intestinal T-cell lymphoma followed by chemotherapy and stem-cell transplant: A case report and review of the literature

BACKGROUND

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare and rapidly progressive intestinal T-cell non-Hodgkin lymphoma associated with a very poor prognosis and a median survival of 7 mo. Advances in the identification of MEITL over the last two decades have led to its recognition as a separate entity. MEITL patients, predominantly male, typically present with vague and nonspecific symptoms and diagnosis is predominantly confirmed at laparotomy. Currently, there are no standardized treatment protocols, and the optimal therapy remains unclear.

CASE SUMMARY

We report a case of MEITL that was initially considered to be gastrointestinal stromal tumor (GIST) and Imatinib was administered for one cycle. The 62-year-old man presented with abdominal pain, abdominal distension, and weight loss of 20 pounds. Within 2 wk, the size of the mass considerably increased on computed tomography scans. The patient underwent surgery followed by chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) and stem-cell transplant. A correct diagnosis of MEITL was established based on postoperative pathology. Immunophenotypically, the neoplastic cells fulfilled the diagnostic criteria for MEITL as they were CD3⁺, CD4⁺, CD8⁺, CD56⁺, and TIA-1⁺.

CONCLUSION

Given that MEITL has no predisposing factor and presents with vague symptoms with rapid progression, the concomitant presence of abdominal symptoms and B symptoms (weight loss, fever, and night sweats) with hypoalbuminemia, anemia, low lymphocytic count and endoscopic findings of diffuse infiltrating type lesions should alert physicians to this rare disease, especially when it comes to Asian patients. Immediate laparotomy should then be carried out followed by chemotherapy and stem-cell transplant.

Surface CD3-negative monomorphic epitheliotropic intestinal T-cell lymphoma

Intestinal T/NK-cell lymphomas include enteropathy-associated T-cell lymphoma (EATL), monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), indolent T-cell lymphoproliferative disorders of the GI tract (ITCLPD), extranodal NK/T-cell lymphoma, nasal type (ENKTL), and intestinal T-cell lymphoma NOS (ITCL-NOS). Here we describe a case of surface CD3-negative MEITL. A 63-year-old Japanese female had a tumor located in the conglomerated ileum, which formed multiple mass lesions. The resected tissue showed a diffuse infiltration of monomorphic medium-sized lymphocytes with epitheliotropism. Flowcytometry using a fresh specimen of the tumor revealed positivity for CD7, CD8, CD38, and CD56, but not surface CD3. On immunohistochemistry, the tumor showed positivity for cytoplasmic CD3, CD8, CD56, TIA-1, Granzyme B, and perforin. EBER with in situ hybridization was negative. Moreover, H3K36me3, which is negative in MEITL with SETD2-mutation, was positive. This is an important case of MEITL due to its oncogenesis.

MONOMORPHIC EPITHELIOTROPIC INTESTINAL T-LYMPHOMA – CASE REPORT

Background: Monomorphic epitheliotropic intestinal T cell lymphoma (MEITL) (formerly termed enteropathy-associated T cell lymphoma, type II) is an extremely rare peripheral T-cell lymphoma that involves the malignant proliferation of a T- lymphocyte in the gastrointestinal tract. Over time, these T cells commonly spread throughout the mucosal lining of a portion of the GI tract (particularly the jejunum and ileum of the small intestine), lead to GI tract nodules and ulcerations, and cause symptoms such as abdominal pain, weight loss, diarrhea, obstruction, bleeding, and/or perforation. Its clinical, morphologic, and immunophenotypic features distinguishing it from the more common Enteropathy Associated T-Lymphoma (previously EATL type I) made it a separate entity. Case report: We present a case of a rare extremely aggressive T cell lymphoma that originates from the gastrointestinal tract, spreads to surrounding organs and is refractory to surgery and chemotherapy. We describe а case report of 79 years old patient with clinical features of acute abdomen, ileus,  treated with surgery two times. During the first surgery partial resection of jejunum was performed. Pathohistology and immunоhistochemistry findings of MEITL. PET/CT scan revealed infiltration of intestinum, uterus, ovarium. During the second operation partial resection of ileum and hysterectomy with adnexectomy was performed. The patient is treated with antracycline-based regimen CHOP21 (4 cycles). Re-evaluation with second PET/CT scan revealed residual tumor on the intestinum and bladder. The patient deteriorate with acute renal failure and multi-organ failure. Despite aggressive treatment with extensive surgery and aggressive anthracycline-based chemotherapy, in a short time the tumor spread to surrounding organs (sigma, bladder). The patient survived 11 months from the initial definitive diagnosis.  Conclusion: MEITL is a challenging primary intestinal T cell lymphoma to treat as the outcome is frequently poor despite surgery and chemotherapy. Most patients are elderly with co-morbidities and they usually present late rendering any therapy ineffective. Young age, early Ann-Arbor/Lugano disease stage, good performance scale status, patients receiving autologous stem cell transplantation and less bulky disease are associated with an improved survival outcome. Further research is needed to incorporate new therapeutic modalities based on molecular research for successful treatment of this aggressive lymphoma.

CD30 + Primary intestinal T-cell lymphoma (unclassified) masquerading as chronic inflammation: a case report

Background

Primary intestinal T-cell lymphomas are uncommon malignancies that pose a diagnostic dilemma, because the clinical features and imaging findings commonly overlap with those encountered in inflammatory bowel diseases.

Case presentation

The current clinical case report describes the clinical history, laboratory findings and histopathological analysis from a patient with non-specific gastrointestinal symptoms with a presumptive clinical diagnosis of inflammatory bowel disease, and two intestinal biopsy specimens with non-specific findings. Due to the persistent symptoms a third biopsy was consistent with primary intestinal T-cell lymphoma, a diagnosis that was elusive for months after the initial presentation. Clinical correlation with laboratory and histopathological findings is required to establish a definitive diagnosis and to further stratify the patients. In addition, the neoplastic cells featured partial expression of CD30, which had relevant therapeutic implications.

Conclusions

Suspicion for an intestinal T-cell lymphoproliferative disorder should always exist in patients with persistent abdominal symptoms with no clear etiology. The current discussion provides a summary and review of the key diagnostic histological features for the classification of primary intestinal T-cell lymphomas. In addition, the discussion describes how specific the histological findings are relevant for the clinical management decisions.

Monomorphic epitheliotropic intestinal T-cell lymphoma comprises morphologic and genomic heterogeneity impacting outcome

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare aggressive T-cell lymphoma most reported in Asia. We performed a comprehensive clinical, pathological and genomic study of 71 European MEITL patients (36 males, 35 females, median age 67 years). The majority presented with gastrointestinal involvement and had emergency surgery, and 40% had stage IV disease. The tumors were morphologically classified into two groups: typical (58%) and atypical (i.e., non-monomorphic or with necrosis, angiotropism or starry-sky pattern) (42%), sharing a homogeneous immunophenotypic profile (CD3+ [98%] CD4- [94%] CD5- [97%] CD7+ [97%] CD8+ [90%] CD56+ [86%] CD103+ [80%] cytotoxic marker+ [98%]) with more frequent expression of TCRgd (50%) than TCRab (32%). MYC expression (30% of cases) partly reflecting MYC gene locus alterations, correlated with non-monomorphic cytology. Almost all cases (97%) harbored deleterious mutation(s) and/or deletion of the SETD2 gene and 90% had defective H3K36 trimethylation. Other frequently mutated genes were STAT5B (57%), JAK3 (50%), TP53 (35%), JAK1 (12.5%), BCOR and ATM (11%). Both TP53 mutations and MYC expression correlated with atypical morphology. The median overall survival (OS) of 63 patients (43/63 only received chemotherapy after initial surgery) was 7.8 months. Multivariate analysis found a strong negative impact on outcome of MYC expression, TP53 mutation, STAT5B mutation and poor performance status while aberrant B-cell marker expression (20% of cases) correlated with better survival. In conclusion, MEITL is an aggressive disease with resistance to conventional therapy, predominantly characterized by driver gene alterations deregulating histone methylation and JAK/STAT signaling and encompasses genetic and morphologic variants associated with very high clinical risk.

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

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

Targeted Next-generation Sequencing Reveals a Wide Morphologic and Immunophenotypic Spectrum of Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma

Primary intestinal T-cell lymphoma (PITL) is highly aggressive and includes celiac disease-related enteropathy-associated T-cell lymphoma (EATL), monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), and primary intestinal peripheral T-cell lymphoma, not otherwise specified (ITCL-NOS). MEITL is the most common PITL in Asia, comprising of monomorphic medium-sized cells typically expressing CD8, CD56, and cytotoxic granules. Occasional cases with intermediate features between MEITL and ITCL-NOS are difficult to be classified and warrant further investigation. We collected 54 surgically resected PITLs from Taiwan, with 80% presenting with bowel perforation. The overall outcome was poor with a median survival of 7 months. Based on histopathology (monomorphic vs. pleomorphic) and immunophenotype, we classified these cases into 4 groups: MEITL with typical immunophenotype (n=34), MEITL with atypical immunophenotype (n=5), pleomorphic PITL with MEITL-like immunophenotype (n=6), and ITCL-NOS (n=9). There was no EATL in our cohort. Targeted next-generation sequencing of the first 3 groups showed highly prevalent loss-of-function mutations for SETD2 (85%, 80%, and 83%, respectively) and frequent activating mutations for STAT5B (64%, 60%, and 50%, respectively) and JAK3 (38%, 20%, and 50%, respectively). In contrast, ITCL-NOS cases had less frequent mutations of SETD2 (56%) and STAT5B (11%) and rare JAK3 mutations (11%). Our results suggest that there is a wider morphologic and immunophenotypic spectrum of MEITL as currently defined in the 2017 WHO classification. MEITL with atypical immunophenotype and PITL with MEITL-like immunophenotype shared clinicopathologic and molecular features similar to MEITL but distinct from ITCL-NOS, indicating that such cases may be considered as immunophenotypic or histopathologic variants of MEITL.

Treatment outcomes of T and natural-killer/T-cell lymphoma with ifosfamide, carboplatin and etoposide chemotherapy

BACKGROUND

Contemporary data of peripheral T-cell lymphoma (PTCL) and natural-killer/T-cell lymphoma (NKTL) patients treated with ifosfamide, carboplatin and etoposide (ICE) are limited.

AIMS

We performed a retrospective analysis to estimate outcomes of ICE-treated PTCL and NKTL patients at three tertiary cancer centres in Singapore.

METHODS AND RESULTS

Patients were identified through lymphoma databases from National Cancer Centre Singapore (NCCS), National University Hospital, Singapore (NUHS), and Singapore General Hospital (SGH). Responses and survival outcomes were determined from electronic medical records. A total of 75 patients with a median age of 50 were included. ICE was used as first-line treatment in 14 patients (19%) and as subsequent lines of treatment in 61 patients (81%). The overall response rates (ORR) for all patients was 63% (40% complete response [CR]). The ORR and CR in the first line were 86% and 64% respectively. At a median follow-up duration of 71.0 months, the median progression-free (PFS) and overall survival (OS) for all patients were 4.4 months (95%CI, 2.7-6.0) and 16 months (95%CI, 8.3-45.4) respectively.

CONCLUSION

In summary, ICE showed high ORR but poor PFS in relapsed/refractory PTCL and NKTL. ORR of ICE in the first line setting appears better than real-world CHOP data and warrants further study.

Single-cell transcriptomics links malignant T cells to the tumor immune landscape in cutaneous T cell lymphoma

Cutaneous T cell lymphoma (CTCL) represents a heterogeneous group of non-Hodgkin lymphoma distinguished by the presence of clonal malignant T cells. The heterogeneity of malignant T cells and the complex tumor microenvironment remain poorly characterized. With single-cell RNA analysis and bulk whole-exome sequencing on 19 skin lesions from 15 CTCL patients, we decipher the intra-tumor and inter-lesion diversity of CTCL patients and propose a multi-step tumor evolution model. We further establish a subtyping scheme based on the molecular features of malignant T cells and their pro-tumorigenic microenvironments: the T_CyEM group, demonstrating a cytotoxic effector memory T cell phenotype, shows more M2 macrophages infiltration, while the T_CM group, featured by a central memory T cell phenotype and adverse patient outcome, is infiltrated by highly exhausted CD8⁺ reactive T cells, B cells and Tregs with suppressive activities. Our results establish a solid basis for understanding the nature of CTCL and pave the way for future precision medicine for CTCL patients.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Genetic profiling and biomarkers in peripheral T-cell lymphomas: current role in the diagnostic work-up

Peripheral T-cell lymphomas are a heterogeneous, and usually aggressive, group of mature T-cell neoplasms with overlapping clinical, morphologic and immunologic features. A large subset of these neoplasms remains unclassifiable with current diagnostic methods ("not otherwise specified"). Genetic profiling and other molecular tools have emerged as widely applied and transformative technologies for discerning the biology of lymphomas and other hematopoietic neoplasms. Although the application of these technologies to peripheral T-cell lymphomas has lagged behind B-cell lymphomas and other cancers, molecular profiling has provided novel prognostic and diagnostic markers as well as an opportunity to understand the biologic mechanisms involved in the pathogenesis of these neoplasms. Some biomarkers are more prevalent in specific T-cell lymphoma subsets and are being used currently in the diagnosis and/or risk stratification of patients with peripheral T-cell lymphomas. Other biomarkers, while promising, need to be validated in larger clinical studies. In this review, we present a summary of our current understanding of the molecular profiles of the major types of peripheral T-cell lymphoma. We particularly focus on the use of biomarkers, including those that can be detected by conventional immunohistochemical studies and those that contribute to the diagnosis, classification, or risk stratification of these neoplasms.

Clinicopathological and molecular genomic features of monomorphic epitheliotropic intestinal T-cell lymphoma in the Chinese population: a study of 20 cases

Background

Monomorphic epitheliotropic T-cell lymphoma (MEITL) is an aggressive non-Hodgkin lymphoma with a high fatality rate. This study was aimed to explore the clinicopathological and molecular genetic features of MEITL in the Chinese population.

Methods

A retrospective analysis was performed based on the clinical manifestations and pathological features of 20 Chinese MEITL. 9 cases with paired diseased-normal tissues were also analyzed for molecular information by whole-exome sequencing.

Results

There were 14 men and 6 women with a median age of 58.5 (28-81) years. 17(17/20) lesions were located in the jejunum or ileum; 13(13/20) cases had ulcers or perforations. Microscopically, except for 1(1/20) case of pleomorphic cells, the monomorphic, middle-sized tumor cells infiltrating into the intestinal epithelial and peripheral intestinal mucosa recess could be seen in the other 19 cases. Immunohistochemistry showed that most of the tumor cells in MEITL were positive for CD3(20/20), CD8(17/20), CD43(19/20), and CD56(15/20), but negative for CD5(20/20). The most frequently mutated genes of these Chinese cases were STAT5B (4/9) and TP53 (4/9), not SETD2(2/9). JAK3 mutations (3/9) were also detected with a high mutated frequency. We demonstrated that mutations of JAK-STAT pathway-related genes and the amplification of Chromosome 9q appeared at the same time in most cases(5/9).

Conclusions

The clinicopathological features were consistent with that in previous western studies, but a special case with pleomorphic cells was found in this study. The co-occurrence of JAK-STAT pathway-related gene mutations and the amplification of Chr9q is a molecular feature of MEITL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01173-5.

The Diverse Roles of γδ T Cells in Cancer: From Rapid Immunity to Aggressive Lymphoma

γδ T cells are unique players in shaping immune responses, lying at the intersection between innate and adaptive immunity. Unlike conventional αβ T cells, γδ T cells largely populate non-lymphoid peripheral tissues, demonstrating tissue specificity, and they respond to ligands in an MHC-independent manner. γδ T cells display rapid activation and effector functions, with a capacity for cytotoxic anti-tumour responses and production of inflammatory cytokines such as IFN-γ or IL-17. Their rapid cytotoxic nature makes them attractive cells for use in anti-cancer immunotherapies. However, upon transformation, γδ T cells can give rise to highly aggressive lymphomas. These rare malignancies often display poor patient survival, and no curative therapies exist. In this review, we discuss the diverse roles of γδ T cells in immune surveillance and response, with a particular focus on cancer immunity. We summarise the intriguing dichotomy between pro- and anti-tumour functions of γδ T cells in solid and haematological cancers, highlighting the key subsets involved. Finally, we discuss potential drivers of γδ T-cell transformation, summarising the main γδ T-cell lymphoma/leukaemia entities, their clinical features, recent advances in mapping their molecular and genomic landscapes, current treatment strategies and potential future targeting options.

Immunophenotyping of intraepithelial lymphocytes in canine chronic enteropathy and intestinal T-cell lymphoma using endoscopic samples

Human enteropathy-associated T-cell lymphoma (EATL) is considered to be derived from intraepithelial lymphocytes (IELs); however, the origin of canine intestinal T-cell lymphoma (ITCL) remains unclear. Histological, immunohistochemical, and clonality examinations were performed using endoscopically collected canine duodenum samples of mucosal lesions of chronic enteropathy (CE; 73 cases) and ITCL without transmural neoplastic mass lesions (64 cases). Histopathological examinations revealed the intraepithelial accumulation of lymphocytes (called "intraepithelial lymphocytosis") in 54/73 CE cases (74%) and the epitheliotropism of neoplastic lymphocytes in 63/64 ITCL cases (98%). Immunohistochemically, IELs in CE with intraepithelial lymphocytosis (IEL⁺CE) were diffusely immunopositive for CD3, with scattered immunopositivity for CD5, CD8, CD20, and granzyme B (GRB). The percentage of CD8⁺ in CD3⁺ IELs was significantly lower in IEL⁺CE than in CE without intraepithelial lymphocytosis (IEL^-CE). Double-labeling immunohistochemistry revealed a high percentage of GRB expression in CD8^- IEL among IEL⁺CE. Among 64 ITCL cases, CD3 was immunopositive in 64 (100%), CD5 in 22 (34%), CD8 in 8 (13%), CD20 in 12 (19%), CD30 in 13 (20%), and GRB in 49 (77%). In CD3⁺ cells, Ki67 immunopositivity was highest in ITCL, intermediate in IEL⁺CE, and lower in IEL^-CE. A clonal TCR gene rearrangement was detected in 1/19 IEL^-CE cases (5%), 15/54 IEL⁺CE (28%), and 38/58 ITCL (66%). These results indicate that the immunophenotype of canine ITCL (CD8^-GRB⁺) is similar to that of the increased IELs in CE. The high proliferative activity and clonality of T cells in IEL⁺CE suggest that canine ITCL originates from these IELs, similar to human EATL.

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

Simple Summary

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

Abstract

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

Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma in the Ileum with Successful Preoperative Endoscopic Evaluation

A 80-year-old man with the history of operations for gastric cancer and adhesive ileus developed abdominal pain. Positron emission computed tomography (CT) showed prominent wall thickening in the ileum with a maximal standardized uptake value of 12.1. Prior CT to diagnose adhesive ileus just taken only 4 months before did not show any masses in the abdomen. Single-balloon enteroscopy via colon showed a protruding mass at approximately 40–50 cm proximal point from the ileum end. Pathological examination of the biopsied specimen showed diffuse infiltration of medium- to large-sized atypical lymphocytes. Immunohistochemistry analysis showed that the atypical cells were positive for CD3 and CD56 and negative for CD8 and CD20. MIB-1 labeling index was extremely high as 80%. Under the diagnosis of intestinal T-cell lymphoma, the patient underwent tumorectomy, leading to the diagnosis of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) after the negativity confirmation of Epstein-Barr virus-encoded mRNAs. The patient recovered with manageable complication and is going to receive chemotherapy. This is the first case of MEITL with extremely rapid progression in the distal ileum to be observed and diagnosed with single-balloon enteroscopy.

Machine Learning Based on Morphological Features Enables Classification of Primary Intestinal T-Cell Lymphomas

The aim of this study was to investigate the feasibility of using machine learning techniques based on morphological features in classifying two subtypes of primary intestinal T-cell lymphomas (PITLs) defined according to the WHO criteria: monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) versus intestinal T-cell lymphoma, not otherwise specified (ITCL-NOS), which is considered a major challenge for pathological diagnosis. A total of 40 histopathological whole-slide images (WSIs) from 40 surgically resected PITL cases were used as the dataset for model training and testing. A deep neural network was trained to detect and segment the nuclei of lymphocytes. Quantitative nuclear morphometrics were further computed from these predicted contours. A decision-tree-based machine learning algorithm, XGBoost, was then trained to classify PITL cases into two disease subtypes using these nuclear morphometric features. The deep neural network achieved an average precision of 0.881 in the cell segmentation work. In terms of classifying MEITL versus ITCL-NOS, the XGBoost model achieved an area under receiver operating characteristic curve (AUC) of 0.966. Our research demonstrated an accurate, human-interpretable approach to using machine learning algorithms for reducing the high dimensionality of image features and classifying T cell lymphomas that present challenges in morphologic diagnosis. The quantitative nuclear morphometric features may lead to further discoveries concerning the relationship between cellular phenotype and disease status.

Monomorphic epitheliotropic intestinal T-cell lymphoma presenting as melena with long-term survival: A case report and review of literature

BACKGROUND

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare primary intestinal T-cell lymphoma, previously known as enteropathy-associated T-cell lymphoma type II. MEITL is an aggressive T-cell lymphoma with a poor prognosis and high mortality rate. The known major complications of MEITL are intestinal perforation and obstruction. Here, we present a case of MEITL that was diagnosed following upper gastrointestinal bleeding from an ulcerative duodenal lesion, with recurrence-free survival for 5 years.

CASE SUMMARY

A 68-year-old female was admitted to our hospital with melena and mild anemia. An urgent esophagogastroduodenoscopy (EGD) revealed bleeding from an ulcerative lesion in the transverse part of the duodenum, for which hemostatic treatment was performed. MEITL was diagnosed following repeated biopsies of the lesion, and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy was administered. She achieved complete remission after eight full cycles of CHOP therapy. At the last follow-up examination, EGD revealed a scarred ulcer and ¹⁸Fluorodeoxyglucose (¹⁸FDG) positron emission tomography/computed tomography showed no abnormal FDG accumulation. The patient has been in complete remission for 68 mo after initial diagnosis.

CONCLUSION

To rule out MEITL, it is important to carefully perform histological examination when bleeding from a duodenal ulcer is observed.

Monomorphic epitheliotropic intestinal T-cell lymphomas: a case report

BACKGROUND

Monomorphic epitheliotropic intestinal T-cell lymphomas (MEITL) is a rare and aggressive subtype of lymphoma. The most common site of origin is small intestine. Patients are often presented with diagnosis of intestinal perforation with abdominal pain as the main consulting symptoms. Because of the deficiency of specific diagnostic measures and effective management, diagnosis is often confirmed in advanced stage with poor prognosis.

CASE PRESENTATION

Here, we introduce a patient who has suffered from abdominal pain and diarrhea, and eventually been diagnosed as Monomorphic epitheliotropic intestinal T-cell lymphomas.

CONCLUSION

MEITL is rare in clinical practice with deficiency of early diagnostic measures and poor prognosis. Therefore, any patient with ambiguous gastrointestinal symptoms or perforation of the digestive tract where the primary lesion is difficult to identify should be alert to the possibility of this disease.

Gastrointestinal lymphoproliferative lesions: a practical diagnostic approach

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

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

Histopathological features and immunophenotyping of canine transmural gastrointestinal lymphoma using full-thickness biopsy samples

To elucidate the histopathological characteristics and immunophenotypes of canine transmural "mass-forming" gastrointestinal lymphomas and plasmacytomas, 83 surgically resected biopsy samples were examined. All lymphomas and plasmacytomas were located in the small or large intestine except for 1 plasmacytoma which was in the stomach. According to the World Health Organization (WHO) classification, B-cell neoplasms (17 cases) included lymphoplasmacytic lymphoma (6/17), plasmacytoma (5/17), follicular lymphoma (3/17), and diffuse large B-cell lymphoma (3/17). Based on nuclear sizes, T-cell neoplasms (66 cases) were broadly divided into large cell lymphoma (LCL; 48/66) and small cell lymphoma (SCL; 18/66). According to the WHO classification, T-cell neoplasms included anaplastic large T-cell lymphoma (ALCL; 10/66), angiotropic T-cell lymphoma (3/66), mixed inflammatory type peripheral T-cell lymphoma (mixed inflammatory type PTCL; 33/66), and PTCL-not otherwise specified (PTCL-NOS; 20/66). Mixed inflammatory type PTCLs were further divided into histiocyte- (27/33) and eosinophil- (6/33) dominant types. Immunohistochemically, lymphoplasmacytic lymphomas were positive for Pax5 (6/6) and IgM (5/6), while plasmacytomas were positive for IgG (5/6) and negative for Pax5. LCLs were immunopositive for granzyme B in 31/48 cases (65%) and CD8 in 9/48 cases (19%), while SCLs were immunopositive for granzyme B in 3/18 cases (17%) and CD8 in 3/18 cases (17%). Furthermore, 8/10 cases (80%) of ALCL and 19/27 cases (70%) of histiocyte-dominant PTCL were immunopositive for granzyme B, whereas 6/20 cases (30%) of PTCL-NOS, 1/6 cases (17%) of eosinophil-dominant PTCL, and no cases of angiotropic T-cell lymphomas were immunopositive for granzyme B. The present study describes the immunophenotypes in different histological types of transmural gastrointestinal lymphomas in the dog.

Primary Gastrointestinal T/NK Cell Lymphoma

Primary gastrointestinal T/NK cell lymphoma (GI-TNKL) is an uncommon and heterogeneous group of lymphoid malignancies. We aimed to investigate their subtype distribution, clinicopathologic characteristics, and clinical outcomes. A total of 38 GI-TNKL cases and their clinical and pathological characteristics were analyzed. GI-TNKL occurred in adults with a median patient age in the sixth decade of life and showed a slight male predominance. The most common histologic type was extranodal NK/T-cell lymphoma, nasal type (ENKTL; 34.2%), followed by monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL; 31.6%), intestinal T-cell lymphoma, NOS (ITCL, NOS, 18.4%), anaplastic large cell lymphoma, ALK-negative (ALCL, ALK-; 13.2%). The small intestine was the primary affected region. More than 90% of patients complained of various GI symptoms and cases with advanced Lugano stage, high IPI score, or bowel perforation that required emergent operation were not uncommon. GI-TNKL also showed aggressive behavior with short progression-free survival and overall survival. This thorough clinical and pathological descriptive analysis will be helpful for accurate understanding, diagnosis, and treatment.

Whole-genome sequencing reveals potent therapeutic strategy for monomorphic epitheliotropic intestinal T-cell lymphoma

Whole genomic and transcriptomic analyses of MEITL revealed multiple potential therapeutic targets. Synergistic effects of pimozide and romidepsin are shown in a well-characterized MEITL PDX model.

Gastrointestinal Tract Lymphomas: A Review of the Most Commonly Encountered Lymphomas

CONTEXT.—

The gastrointestinal (GI) tract is the most common site of extranodal non-Hodgkin lymphoma, accounting for 20% to 40% of all extranodal lymphomas. The majority of these are systemic processes secondarily involving the GI tract. Primary GI lymphomas are less common, accounting for approximately 10% to 15% of all non-Hodgkin lymphoma. Most non-Hodgkin lymphoma involving the GI tract are of B-cell lineage, of which diffuse large B-cell lymphoma is the most common subtype, irrespective of location.

OBJECTIVE.—

To review the lymphoproliferative neoplasms of B-cell and T-cell lineage involving the luminal GI tract according to the most prevalent subtypes at each anatomic site.

DATA SOURCE.—

Systematic search of the PubMed database for updated literature on GI lymphomas epidemiology, subtypes, clinical, endoscopic, and genetic findings. Histologic images are derived from our collection of clinical cases.

CONCLUSIONS.—

The GI tract is the most common site of extranodal lymphoproliferative neoplasms. Recognition of the most frequently encountered GI lymphomas is imperative for patient management and treatment.

Diagnostic approach to T- and NK-cell lymphoproliferative disorders in the gastrointestinal tract

Most gastrointestinal NK and T cell lymphomas are aggressive in behavior, although in recent years a subset of indolent lymphoproliferative disorders have been described, which must be distinguished from their more malignant mimics. Intestinal T-cell lymphomas may arise from intra-epithelial lymphocytes and display epitheliotropism, such as enteropathy-associated T-cell lymphoma and monomorphic epitheliotropic intestinal T-cell lymphoma. They are both aggressive in behavior but differ in their clinic-pathological features. On the other hand, intra-epithelial lymphocytes are not prominent in intestinal T-cell lymphoma, NOS, which is a diagnosis of exclusion and probably represents a heterogeneous group of entities. Indolent lymphoproliferative disorders of NK- and T-cells of both CD8 and CD4 subsets share a chronic, recurring clinical course but display differences from each other. CD8+ T-cell lymphoproliferative disorder of GI tract has a low proliferative fraction and does not progress nor undergo large cell transformation. Whilst NK-cell enteropathy runs an indolent clinical course, it may display a high proliferation fraction. On the other hand, CD4+ indolent T-cell lymphoproliferative disorder displays variable proliferation rates and may progress or transform after a number of years. In Asia and South America, it is not uncommon to see involvement of the gastrointestinal tract by EBV-associated extranodal NK/T cell lymphoma, nasal type, which must be distinguished from NK cell enteropathy and EBV-associated mucocutaneous ulcers.

New developments in non-Hodgkin lymphoid malignancies

The revised fourth edition of the World Health Organization (WHO) Classification of Tumours of Haematopoietic and Lymphoid Tissues (2017) reflects significant advances in understanding the biology, genetic basis and behaviour of haematopoietic neoplasms. This review focuses on some of the major changes in B-cell and T-cell non-Hodgkin lymphomas in the 2017 WHO and includes more recent updates. The 2017 WHO saw a shift towards conservatism in the classification of precursor lesions of small B-cell lymphomas such as monoclonal B-cell lymphocytosis, in situ follicular and in situ mantle cell neoplasms. With more widespread use of next generation sequencing (NGS), special entities within follicular lymphoma and mantle cell lymphoma were recognised with recurrent genetic aberrations and unique clinicopathological features. The diagnostic workup of lymphoplasmacytic lymphoma and hairy cell leukaemia has been refined with the discovery of MYD88 L265P and BRAF V600E mutations, respectively, in these entities. Recommendations in the immunohistochemical evaluation of diffuse large B-cell lymphoma include determining cell of origin and expression of MYC and BCL2, so called 'double-expressor' phenotype. EBV-positive large B-cell lymphoma of the elderly has been renamed to recognise its occurrence amongst a wider age group. EBV-positive mucocutaneous ulcer is a newly recognised entity with indolent clinical behaviour that occurs in the setting of immunosuppression. Two lymphomas with recurrent genetic aberrations are newly included provisional entities: Burkitt-like lymphoma with 11q aberration and large B-cell lymphoma with IRF4 rearrangement. Aggressive B-cell lymphomas with MYC, BCL2 and/or BCL6 rearrangements, so called 'double-hit/triple-hit' lymphomas are now a distinct entity. Much progress has been made in understanding intestinal T-cell lymphomas. Enteropathy-associated T-cell lymphoma, type II, is now known to not be associated with coeliac disease and is hence renamed monomorphic epitheliotropic T-cell lymphoma. An indolent clonal T-cell lymphoproliferative disorder of the GI tract is a newly included provisional entity. Angioimmunoblastic T-cell lymphoma and nodal T-cell lymphomas with T-follicular helper phenotype are included in a single broad category, emphasising their shared genetic and phenotypic features. Anaplastic large cell lymphoma, ALK- is upgraded to a definitive entity with subsets carrying recurrent rearrangements in DUSP22 or TP63. Breast implant-associated anaplastic large cell lymphoma is a new provisional entity with indolent behaviour. Finally, cutaneous T-cell proliferations include a new provisional entity, primary cutaneous acral CD8-positive T-cell lymphoma, and reclassification of primary small/medium CD4-positive T-cell lymphoma as lymphoproliferative disorder.

Early central nervous system relapse of monomorphic epitheliotropic intestinal T-cell lymphoma after cord blood transplantation

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare subtype of intestinal T-cell lymphoma that occurs mostly in Asia. CHOP-like therapy is usually selected, but the prognosis is very poor. This report concerns a 43-year-old woman with newly diagnosed stage IVA MEITL. The patient obtained a partial response after 4 cycles of GDP (gemcitabine, dexamethasone, cisplatin) and achieved a complete response (CR) after cord blood transplantation (CBT) conditioned with total body irradiation, cyclophosphamide, and cytarabine. Seven months after transplantation, the patient experienced cognitive impairment. Magnetic resonance imaging of the brain showed a high-intensity lesion in the right cerebral peduncle and internal capsule. A cerebrospinal fluid examination confirmed central nervous system (CNS) relapse of MEITL. After 3 cycles of MPV (methotrexate, procarbazine, vincristine) followed by whole-brain radiotherapy, her cognitive impairment improved. Due to disease progression, she died 6 months after CNS relapse. Given the CNS relapse after achieving a CR with GDP and CBT in this patient, CNS prophylaxis during first-line therapy may be beneficial in the treatment of MEITL.

Recent advances upper gastrointestinal lymphomas: molecular updates and diagnostic implications

Approximately one-third of extranodal non-Hodgkin lymphomas involve the gastrointestinal (GI) tract, with the vast majority being diagnosed in the stomach, duodenum, or proximal small intestine. A few entities, especially diffuse large B-cell lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, represent the majority of cases. In addition, there are diseases specific to or characteristic of the GI tract, and any type of systemic lymphoma can present in or disseminate to these organs. The recent advances in the genetic and molecular characterisation of lymphoid neoplasms have translated into notable changes in the classification of primary GI T-cell neoplasms and the recommended diagnostic approach to aggressive B-cell tumours. In many instances, diagnoses rely on morphology and immunophenotype, but there is an increasing need to incorporate molecular genetic markers. Moreover, it is also important to take into consideration the endoscopic and clinical presentations. This review gives an update on the most recent developments in the pathology and molecular pathology of upper GI lymphoproliferative diseases.

Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma in Asia Frequently Shows SETD2 Alterations

Simple Summary

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare primary T-cell lymphoma of the digestive tract that is characterized by an aggressive clinical course. The aim of this study was to analyze the clinicopathological characteristics and genomic profile of Asian MEITL. In this study, nine cases of Japanese MEITL were analyzed by targeted Next Generation Sequencing and immunohistochemistry and were integrated with previously reported whole-genome copy number microarray-based assay data. All cases showed alterations of the tumor suppressor gene SETD2 and mutations in one or more genes of the JAK/STAT pathway. Therefore, we concluded that the combination of epigenetic deregulation and cell signaling activation may represent a major oncogenic event in the pathogenesis of Asian MEITL, similar to Western MEITL.

Abstract

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare primary T-cell lymphoma of the digestive tract derived from intraepithelial lymphocytes and characterized by an aggressive clinical course. In this study, nine cases of Japanese MEITL were analyzed by targeted Next Generation Sequencing (NGS) and immunohistochemistry and were integrated with previously reported whole-genome copy number microarray-based assay data. The highlight of our findings is that all cases showed alterations of the tumor suppressor gene SETD2 by mutations and/or loss of the corresponding 3p21 locus. We also demonstrated that all cases showed mutations in one or more genes of JAK/STAT pathway. Therefore, the combination of epigenetic deregulation and cell signaling activation represent major oncogenic events in the pathogenesis of MEITL in Asian MEITL, similar to Western MEITL.

Monomorphic Epitheliotropic Intestinal T-cell Lymphoma Involving the Lung and Brain: A Rare Case Study

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a primary intestinal T-cell lymphoma and other organ involvement is very rare. A rare case of MEITL involving the lung and brain is herein reported. The patient developed panperitonitis with a small intestinal perforation, and emergency surgery was performed. The pathological findings from the surgical specimens demonstrated atypical lymphoid cells which were positive for CD3, CD8, and CD56. Moreover, the pathological findings of lung specimens taken by bronchoscopy were consistent with those of the small intestine. It is therefore important to include the possibility of MEITL in the differential diagnosis of cancer patients.

American Registry of Pathology Expert Opinions: Recommendations for the diagnostic workup of mature T cell neoplasms

The diagnosis of T-cell lymphomas is highly challenging and requires an integrated approach in which clinical, morphologic, immunophenotypic and molecular data are incorporated into the diagnosis. Under the auspices of the American Registry of Pathology, the authors met to discuss this topic with the goal to provide practical and useful recommendations for pathologists when evaluating T-cell lymphomas. In this review, we discuss the diagnostic findings and workup for the various types of nodal T-cell lymphoma including anaplastic large cell lymphoma, nodal peripheral T-cell lymphoma not otherwise specified (PTCL-NOS), and PTCL with a T follicular helper (TFH) phenotype. We review clinicopathologic and immunophenotypic features (including flow cytometry panels) helpful in the differential diagnosis of mature T-cell lymphomas presenting in the peripheral blood and bone marrow, and we discuss some of the more common extranodal-based T-cell lymphomas including extranodal natural killer/T-cell lymphoma of nasal and non-nasal type, gamma delta T cell lymphomas, and aggressive and indolent T- and NK-lymphoproliferative disorders involving the gastrointestinal tract. Mycosis fungoides and most other cutaneous T-cell lymphomas are not the focus of this review, although the differential diagnosis of Sezary syndrome from mycosis fungoides is covered. We do not intend for these recommendations to be anything other than suggestions that will hopefully spur on additional discussion, and perhaps eventually evolve into a consensus approach for the workup of T-cell lymphomas.

Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma With Extraintestinal Areas of Peripheral T-Cell Lymphoma Involvement

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a primary intestinal T-cell lymphoma, previously known as enteropathy-associated T-cell lymphoma (EATL) type II. Its clinical, morphologic, and immunophenotypic features distinguishing it from the more common EATL (previously EATL type I) made it a separate entity. Unlike EATL, MEITL typically is noted in Asian, Hispanic, and indigenous populations; it is rarer in native European and Caucasian populations. Due to its poor prognosis, it needs to be distinguished from inflammatory diseases and less aggressive T-cell lymphomas. We present an unusual case of MEITL in a Caucasian patient who developed nonspecific GI symptoms and was diagnosed with MEITL of the jejunum, mesenteric lymph nodes, and multiple extraintestinal sites based on histology, immunophenotype, molecular testing, and imaging. Despite aggressive treatment, he expired about seven months after the definitive diagnosis.

Chidamide based combination regimen for treatment of monomorphic epitheliotropic intestinal T cell lymphoma following radical operation: Two case reports

BACKGROUND

Monomorphic epitheliotropic intestinal T cell lymphoma (MEITL) is a rare extra-nodal T-cell lymphoma that has uniformly aggressive features with a poor prognosis. No standardized treatment protocols have been established. Previous experience has demonstrated favorable outcomes with combination chemotherapy followed by autologous hematopoietic stem cell transplant. However, many patients are unable to tolerate the toxicities. Chidamide is a new histone deacetylase inhibitor that has shown preferential efficacy in mature T-cell lymphoma.

CASE SUMMARY

We herein present two cases of MEITL who were both intermediate risk according to enteropathy-associated T cell lymphoma prognostic index. Case one was a 61-year-old man. He complained of upper abdominal pain and intermittent black stool for 2 mo. Imaging examination revealed that the intestinal wall was thickened. He received a partial excision of the small intestine. A chidamide-based combination regimen was given postoperatively. Eleven months later, he presented with recurrence in the bilateral lungs. He passed away 15 mo after his diagnosis. Case two was a 35-year-old woman who complained of abdominal distention for 1 mo. Positron emission tomography/computed tomography demonstrated wall thickening of the small intestine and upper sigmoid colon. Colon perforation and septic shock occurred on the fourth day of her admission. She was treated by sigmoid colostomy. Chidamide-based combination therapy was then provided. She was recurrence-free for 6 mo until lesions were found in the bilateral brain and lived for 17 mo since her diagnosis. Compared to historical data, chidamide seems to improve the prognosis of MEITL slightly.

CONCLUSION

MEITL is a type of aggressive lymphoma. Chidamide is a new promising approach for the treatment of MEITL.

Update on lymphoproliferative disorders of the gastrointestinal tract: disease spectrum from indolent lymphoproliferations to aggressive lymphomas

This paper summarizes two sessions of the workshop during the XIX meeting of the European Association for Haematopathology (EAHP) held in Edinburgh in September 2018 dedicated to lymphomas of the gastrointestinal tract. The first session focused on the clinical and pathological features of primary gastrointestinal T cell and NK-cell lymphoproliferative disorders. The distinction between precursor lesions (RCD type 2) and enteropathy-associated T cell lymphoma were stressed, including the discussion of new diagnostic markers for the identification of aberrant phenotypes. Indolent T cell lymphoproliferative disorders of the gastrointestinal tract cases showed phenotypic heterogeneity with novel molecular alterations in few cases, such as STAT3-JAK2 fusion. In addition, novel clonal markers of disease, such as AXL and JAK3 somatic variants support the neoplastic nature of NK-cell enteropathy. The session on gastrointestinal tract B cell lymphoproliferations was dedicated to B cell lymphoproliferative disorders that arise primarily in the gastrointestinal tract (i.e., duodenal-type follicular lymphoma) or preferentially involve the digestive tract, such as large B cell lymphoma with IRF4 translocation and mantle cell lymphoma (MCL), including diverse molecular subtypes (i.e., CCND3-positive MCL mimicking MALT lymphoma). Challenging cases of high-grade B cell lymphomas with complex genetic profiles demonstrated the usefulness of novel molecular diagnostic methods such as targeted NGS to identify high-risk genetic features with potential clinical impact.

Epstein-Barr virus-associated T- and NK-cell lymphoproliferative diseases: an update and diagnostic approach

Epstein-Barr virus (EBV)-positive T-cell and natural killer (NK)-cell lymphoproliferative diseases (EBV-TNKLPD) are a group of uncommon disorders characterised by EBV infection of T- and NK-cells. As a group, EBV-TNKLPD are more commonly encountered in Asians and Native Americans from Central and South America compared to Western populations. They encompass a spectrum of entities that range from non-neoplastic lesions such as EBV-associated haemophagocytic lymphohistiocytosis (EBV-HLH) to more chronic conditions with variable outcomes such as chronic active EBV infections (CAEBV) of T- and NK-cell type (cutaneous and systemic forms) and malignant diseases such as systemic EBV-positive T-cell lymphoma of childhood, aggressive NK-cell leukaemia, extranodal NK/T-cell lymphoma, nasal-type, and primary EBV-positive nodal T/NK-cell lymphoma. Due to their rarity, broad clinicopathological spectrum and significant morphological and immunophenotypic overlap, the diagnosis and precise classification of EBV-TNKLPD often pose a challenge to clinicians and pathologists. Correct classification of this group of rare diseases relies heavily on the age of onset, disease presentation, duration of symptoms and cell of origin (T- vs NK-cell lineage). In this review, we provide an update on the clinicopathological and molecular features of the various EBV-TNKLPD entities occurring in non-immunocompromised patients and present a practical algorithmic approach for the general pathologist who is confronted with these disorders in routine clinical practice.