Indolent T- and NK-cell lymphoproliferative disorders of the gastrointestinal tract: a review and update

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.

Advances in Nonresponsive and Refractory Celiac Disease

Nonresponsive celiac disease (CeD) is relatively common. It is generally attributed to persistent gluten exposure and resolves after correction of diet errors. However, other complications of CeD and disorders clinically mimicking CeD need to be excluded. Novel therapies are being evaluated to facilitate mucosal recovery, which might benefit patients with nonresponsive CeD. Refractory CeD (RCeD) is rare and is divided into 2 types. The etiology of type I RCeD is unclear. A switch to gluten-independent autoimmunity is suspected in some patients. In contrast, type II RCeD represents a low-grade intraepithelial lymphoma. Type I RCeD remains a diagnosis of exclusion, requiring ruling out gluten intake and other nonmalignant causes of villous atrophy. Diagnosis of type II RCeD relies on the demonstration of a clonal population of neoplastic intraepithelial lymphocytes with an atypical immunophenotype. Type I RCeD and type II RCeD generally respond to open-capsule budesonide, but the latter has a dismal prognosis due to severe malnutrition and frequent progression to enteropathy-associated T-cell lymphoma; more efficient therapy is needed.

Indolent T-Cell/Natural Killer-Cell Lymphomas/Lymphoproliferative Disorders of the Gastrointestinal Tract-What Have We Learned in the Last Decade?

Primary gastrointestinal (GI) T-cell and natural killer (NK)-cell lymphomas/lymphoproliferative disorders (LPD) are uncommon, and they are usually aggressive in nature. However, T-cell and NK-cell lymphoma/LPD of the GI tract with indolent clinical course has been reported over the past 2 decades. Indolent T-cell LPD was formally proposed a decade ago in 2013 and 4 years later recognized as a provisional entity by the revised fourth edition of WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues in 2017. Indolent T-cell LPD of the GI tract has been changed to indolent T-cell lymphoma of the GI tract as a distinct entity by the fifth edition of WHO Classification of Haematolymphoid Tumours, but the International Consensus Classification of mature lymphoid neoplasms prefers indolent clonal T-cell LPD of the GI tract instead. In the past decade, indolent lymphoma/LPD of the GI tract has been expanded to NK cells, and as such, indolent NK-cell LPD of the GI tract was recognized as an entity by both the fifth edition of WHO Classification of Haematolymphoid Tumours and the International Consensus Classification. The underlying genetic/molecular mechanisms of both indolent T-cell lymphoma/LPD of the GI tract and indolent NK-cell LPD of the GI tract have been recently discovered. In this review, we describe the history; salient clinical, cytohistomorphologic, and immunohistochemical features; and genetic/genomic landscape of both entities. In addition, we also summarize the mimics and differential diagnosis. Finally, we propose future directions with regard to the pathogenesis and clinical management.

Histologic characterization of the major duodenal papilla and association with concurrent biliary, pancreatic, and intestinal pathology in cats

Conjoining of the major pancreatic duct and common bile duct at the major duodenal papilla (MDP) is suspected to predispose cats to the clinical syndrome of "triaditis." However, microanatomy of the MDP or presence of lesions at the MDP has not been assessed in cats with or without triaditis. The aims of this study were to characterize feline MDP histomorphology and to identify associations between MDP anatomy/disease and the presence of biliary, pancreatic, or intestinal inflammation or neoplasia. Histologic assessment was prospectively performed on the MDP, duodenum, jejunum, ileum, liver, and pancreas from 124 client-owned cats undergoing postmortem examination. The majority of cats (104/124, 84%) had a complex ductular network at the MDP, with no distinction between pancreatic and common bile ducts. Lymphoid aggregates at the MDP were common (63/124, 51%). Inflammation of the MDP (MDPitis) was present in 35 of 124 cats (28%) and was often concurrent with cholangitis, pancreatitis, or enteritis (32/35, 91%), but was only associated with enteritis (19/35, 54%, P < .05). Triaditis was less common (19/124, 15%), but was associated with both conjoined MDP anatomy (19/19, 100%, P < .05) and MDPitis (12/19, 63%, P < .05). Neoplasia was present in 37 of 124 cats (29%), with lymphoma (28/37, 78%) predominating. Enteropathy-associated T-cell lymphoma type 2 (EATL2) was most common (n = 16/37, 43%) and was associated with triaditis and MDPitis (P < .05). These findings suggest that anatomy, immune activation, and/or inflammation of the MDP may play a role in the pathogenesis of triaditis. Further studies are needed to elucidate the relationships between triaditis, MDPitis, and EATL2.

Lymphomas and Amyloid in the Gastrointestinal Tract

Lymphoproliferative disorders are a heterogeneous group of neoplasms with varying clinical, morphologic, immunophenotypic, and genetic characteristics. A subset of lymphomas have a proclivity for the gastrointestinal tract, although this region may also be involved by systemic lymphomas. In addition, a number of indolent lymphoproliferative disorders of the gastrointestinal tract have been defined over the past decade, and it is important to accurately differentiate these neoplasms to ensure that patients receive the proper management. Here, the authors review lymphoid neoplasms that show frequent gastrointestinal involvement and provide updates from the recent hematolymphoid neoplasm classification systems.

Metronomic chemotherapy for indolent T-cell lymphoproliferative disorder of the gastrointestinal tract

The present study proposes metronomic chemotherapy (CPT), including prednisolone, cyclophosphamide, and thalidomide, as a treatment for patients with severe symptomatic indolent T‐cell lymphoproliferative disorder of the gastrointestinal tract. The encouraging efficacy and excellent safety profile of CPT suggest the clinical potential of this combination.

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.

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.

Indolent Lymphoproliferative T-Cell Disorders Associated With Gastrointestional Disease: Diagnostic Challenges and Outcomes

Lymphoproliferative diseases arise when the physiological mechanisms that control the proliferation of T and B lymphocytes are disrupted, resulting in an uncontrolled and autonomous increase in immune cells leading to lymphocytosis and lymphadenopathy, and often to the involvement of extranodal sites. The differential diagnosis of malignant T cell tumors involves other neoplasms and non-clonal T cell proliferations. Immunological markers are essential, as a first step, to distinguish between T-cell and non-T-cell disorders. It must be established based on the configuration of the genes of the TCR chain to rule out that the picture is not reactive to other underlying diseases. This clinical review and accompanying case reports highlight the diagnostic challenges associated with indolent lymphoproliferative T-cell disorders, which in many cases may represent the clinical manifestation of a single disease. Particularly we focus on gastrointestinal manifestations that could be expression either of lymphoproliferative disorder either of autoimmune disease either of both. The correct interpretation of the different clinical situations can help in the diagnostic and therapeutic process.

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.

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.

Visible intestinal peristalsis and chronic diarrhea due to a rare lymphoproliferative disease

We present the case of a 45-year-old man with watery diarrhea for 2 years, leading to marked weight loss (52 kg). On admission, the patient presented with pallor, dehydration and cachexia. Abdominal examination revealed increased bowel sounds, painful and visible intestinal peristalsis, suggesting intestinal obstruction. There was no response to a gluten-free diet and nutritional support. Finally, the patient developed pulmonary infection, septic shock and died 3 months after admission. The diagnosis of CD4+/CD8+ indolent T-cell lymphoma of the GI tract was made post-mortem.

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?

Intestinal presentation of non-Hodgkin lymphoma: Case report

Background

MEITL (monomorphic epitheliotropic intestinal T-cell lymphoma) is a rare primary intestinal T-cell lymphoma associated with high mortality rate. Being intestinal this implies difficult diagnostic workup and management.

Case

We present a case of 59-year-old male presented with abdominal pain and found to have 15 × 11 cm mass in the right iliac fossa. Decision for surgical excision was retained and the Pathological examination determined monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) with CD30 positive immune-histochemical profile.

Conclusion

MEITL is a rare entity which retains challenging diagnosis and management as well as variable immune-histochemical profile. In the absence of clear guidelines for the management of intestinal manifestation of lymphoma, surgical approach may have its indications.

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Intestinal manifestation of lymphoma is a rare entity.

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This report highlights the surgical indication in establishing the diagnosis and the management.

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MEITL may present with variable immune-histochemical profile being CD30 positive.

Indolent T-Cell Lymphoproliferative Disorders of the Gastrointestinal Tract (iTLPD-GI): A Review

Simple Summary

This review aims to better define the clinical, pathological, and molecular features of the novel lymphoproliferative disease termed “indolent T-cell lymphoproliferative disorder of the gastro-intestinal tract (iTLPD-GI)”, to discuss potential pitfalls in differentiating this entity from other neoplastic and non-neoplastic disorders arising at the same site, and to point out a biomarker-based approach to the diagnosis.

Abstract

iTLPD-GI is a low-grade clonal T-cell lymphoproliferative disease arising in GI organs. It is an uncommon disease, and only recently has it been enlisted as a distinct provisional entity in the current WHO Classification. Data from the literature disclose high heterogeneity in terms of pathological and molecular features; on the other hand, establishing an accurate diagnosis of iTLPD-GI is of pivotal importance, since treatment options are different from that of other, more frequent lymphomas that arise in the gastrointestinal tract. In this review, we aimed to better define this novel entity, and to identify useful diagnostic biomarkers; moreover, we provide a biomarker-based approach to the diagnosis and describe the most common issues in differentiating iTLPD-GI from other neoplastic and non-neoplastic disorders.

Feline low-grade intestinal T cell lymphoma: a unique natural model of human indolent T cell lymphoproliferative disorder of the gastrointestinal tract

Indolent T cell lymphoproliferative disorder (LPD) of the gastrointestinal tract (GI-TLPD) is a rare human primary gastrointestinal T cell lymphoma that was recently included in the 2016 revision of the World Health Organization classification of lymphoid neoplasms. Low-grade intestinal T cell lymphoma (LGITL), an emerging disease in the domestic cat, shares a number of features with human GI-TLPD. In this prospective study, we determined whether feline LGITL might serve as a model of human GI-TLPD. We analyzed clinical, laboratory, and radiological data and performed histopathological and molecular studies on small intestinal biopsies from 22 domestic cats diagnosed with LGITL. This cancer mostly affects aging cats, is associated with nonspecific gastrointestinal tract signs, and is usually characterized by an indolent course. A histopathological analysis indicated that LGITL was mainly located in the jejunum. The small intestinal lamina propria was infiltrated by large numbers of small CD3+ T cell lymphocytes with various CD4 and CD8 expression profiles (CD4+ CD8- (4 out of 11, 36%), CD4- CD8+ (3 out of 11, 27%), and CD4- CD8- (4 out of 11, 36%)). Intraepithelial lymphocyte (IEL) counts were elevated in all cases. Ki67 was expressed in lamina propria lymphocytes and IELs at a low level (<30%). Most LGITLs were labelled by antibodies against phosphorylated STAT5, but were negative for CD56 and phosphorylated STAT3. T cell receptor gamma chain gene monoclonality was found in 86% of cases. These findings confirmed that feline LGITL shares clinical and histopathological features with human GI-TLPD. Feline LGITL may therefore constitute a relevant model of the human disease.

Lymphoma Classification

Twenty-five years after the Revised European American Classification of Lymphoid Neoplasms classification was published, its principle of an integrative approach to disease definition based on several parameters still prevails and has been adopted and expanded in the following World Health Organization classifications of tumors of the hematopoietic organs. The latest World Health Organization classification revised in 2017 comprises more than 80 entities of mature lymphoid neoplasms (B-cell, T-cell, and Hodgkin lymphomas), which are defined according to their morphology, immunophenotype, genetic lesions and molecular profiles, clinical features, and cellular derivation. The classification also recognizes both incipient and indolent lymphoid neoplasms with a low potential of progression. In this review, we highlight some of the new data and recent modifications introduced in the 2017 classification.

Untargeted metabolomic analysis in cats with naturally occurring inflammatory bowel disease and alimentary small cell lymphoma

Feline chronic enteropathy (CE) is a common gastrointestinal disorder in cats and mainly comprises inflammatory bowel disease (IBD) and small cell lymphoma (SCL). Differentiation between IBD and SCL can be diagnostically challenging. We characterized the fecal metabolome of 14 healthy cats and 22 cats with naturally occurring CE (11 cats with IBD and 11 cats with SCL). Principal component analysis and heat map analysis showed distinct clustering between cats with CE and healthy controls. Random forest classification revealed good group prediction for healthy cats and cats with CE, with an overall out-of-bag error rate of 16.7%. Univariate analysis indicated that levels of 84 compounds in cats with CE differed from those in healthy cats. Polyunsaturated fatty acids held discriminatory power in differentiating IBD from SCL. Metabolomic profiles of cats with CE resembled those in people with CE with significant alterations of metabolites related to tryptophan, arachidonic acid, and glutathione pathways.

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.

Overview of Gastrointestinal Lymphoproliferative disorders✰

Lymphoproliferative processes which occur in the gastrointestinal tract range from benign reactive processes such as follicular hyperplasia (rectal tonsil) to high grade malignant lymphomas and histiocytic sarcoma. The WHO Classification of Tumors: Digestive System Tumors, 5th Edition was published in 2019 and shows several impactful changes as compared to the 4th Edition published in 2010. WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues 2017 also included detailed changes in hematopoietic neoplasms within the gastrointestinal tract. New entities or renamed hematolymphoid lesions include monomorphic epitheliotropic intestinal T-cell lymphoma, duodenal-type follicular lymphoma, intestinal T-cell lymphoma, NOS and indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. A brief overview of WHO classification of digestive tumors and WHO classification of tumors of hematopoietic and lymphoid tissue is discussed focusing on the changes in the most recent WHO texts. In depth discussions will be presented in other papers in this series.

Indolent T-cell lymphoproliferative disorder of the stomach successfully treated by radiotherapy

Successful treatment of indolent T-cell lymphoproliferative disorder of the gastrointestinal tract (ITLPDGI) by chemotherapy is rare and watchful waiting is often performed for asymptomatic patients. We report a case of ITLPDGI successfully treated by involved field radiotherapy (IFRT). The patient presented with slow ITLPDGI localised to the stomach with mild symptoms. IFRT (30 Gy/20f) was administered, after which endoscopy revealed resolution of lesions and blood vessel appearance, and absence of proliferating abnormal lymphocytes was confirmed by biopsy. The patient remains lymphoma-free 1 year post-treatment. Although long-term follow-up and additional cases are essential for the evaluation of IFRT as a treatment option for localised ITLPDGL, complete remission after relatively low-dose IFRT is promising, particularly as this has been rarely achieved by chemotherapy.

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.

Indolent T-cell lymphoproliferative disorder of the gastrointestinal tract: a tricky diagnosis of a gastric case

Background

Indolent T-cell lymphoproliferative disorder of the gastrointestinal tract is a rare low-grade clonal lymphoid proliferation, included as a provisional entity in the current World Health Organization classification. The disease is generally localized to the gastrointestinal tract, mainly small bowel and colon. Involvement of other organs is infrequently reported. The majority of patients show a protracted clinical course with persistent disease. A prolonged survival, even without treatment, is common.

Case presentation

A 28-year-old woman had a 2-year history of dyspepsia and lactose intolerance. Autoimmune diseases and celiac disease were excluded. No gross lesions were identified by endoscopy. Multiple gastric biopsies showed a small-sized lymphoid infiltrate, expanding the lamina propria, with a non-destructive appearance. The lymphoid cells were positive for CD3, CD4, CD5, CD7 and negative for CD20, CD8, CD56, CD103, PD1, CD30, ALK1, CD10, BCL6, perforin, TIA-1, Granzyme B and Epstein-Barr virus-encoded RNA. KI-67 index was low (5%). Molecular analysis revealed a clonal T-cell receptor γ rearrangement. Bone marrow was microscopically free of disease, but molecular testing identified the same T-cell receptor γ rearrangement present in the gastric biopsies. After the diagnosis of indolent T-cell lymphoproliferative disorder of the gastrointestinal tract, the patient received steroid therapy, only for 2 months. She is alive, with a stable disease restricted to the stomach, at 12 months from diagnosis.

Conclusions

Indolent T-cell lymphoproliferative disorder is usually a disease of adulthood (median age: 51 yrs). The small bowel and colon are the sites most commonly involved. Our case occurred in a young woman and affected the stomach, sparing small intestine and colon. Clonality testing identified involvement of bone marrow, a site infrequently affected in this disease. Our aim is focusing on the main diagnostic issues. If appropriate immunostainings and molecular analysis are not performed, the subtle infiltrate may be easily overlooked. The risk of misdiagnosis as more aggressive lymphomas, causing patient overtreatment, needs also to be considered.

Indolent T cell lymphoproliferative disorder of the gastrointestinal tract: an uncommon case with lymph node involvement and the classic Hodgkin's lymphoma

Here we describe an unusual case of an indolent CD8+ T-cell lymphoproliferative disorder in the gastrointestinal tract (ITCLD-GT) accompanied by neck lymph node infiltration and new onset of classic Hodgkin's lymphoma after two years follow-up. Previously, this 42-year-old Asian man suffered from diarrhea and abdominal pain for two years. Intestinal biopsies showed a group of small to intermediate-sized lymphocytes which were monomorphic as well as arranged in a nodular pattern with no clear boundary and were diagnosed as ITCLD-GT. He did not receive chemotherapy or have any disease progression in the gastrointestinal tract (GIT) during the follow-up until a development of neck lymphadenopathy, which led to an eventual mixed cellularity type of Hodgkin's lymphoma, one type of classic HL diagnosis. Interestingly, besides the Hodgkin's cells, the same pathological T-cells in the GIT were present in the Hodgkin's lymphoma lesions. These two pathological T cells in GIT and neck lymph node had the identical histopathological and molecular abnormalities that confirmed the abenteric distant infiltration of ITCLD-GT to the neck lymph node in this patient. This is the first case of ITCLD-GT that has a definite distant lymph node invasion. ITCLD-GT usually has a relatively good prognosis but patients with ITCLD-GT may have abenteric distant infiltration. Thus, long-term follow-up and further study of the underlying mechanisms of this process are necessary.

Indolent T cell lymphoproliferative disorder of the gastrointestinal tract: an uncommon case with lymph node involvement and the classic Hodgkin's lymphoma

Here we describe an unusual case of an indolent CD8+ T-cell lymphoproliferative disorder in the gastrointestinal tract (ITCLD-GT) accompanied by neck lymph node infiltration and new onset of classic Hodgkin's lymphoma after two years follow-up. Previously, this 42-year-old Asian man suffered from diarrhea and abdominal pain for two years. Intestinal biopsies showed a group of small to intermediate-sized lymphocytes which were monomorphic as well as arranged in a nodular pattern with no clear boundary and were diagnosed as ITCLD-GT. He did not receive chemotherapy or have any disease progression in the gastrointestinal tract (GIT) during the follow-up until a development of neck lymphadenopathy, which led to an eventual mixed cellularity type of Hodgkin's lymphoma, one type of classic HL diagnosis. Interestingly, besides the Hodgkin's cells, the same pathological T-cells in the GIT were present in the Hodgkin's lymphoma lesions. These two pathological T cells in GIT and neck lymph node had the identical histopathological and molecular abnormalities that confirmed the abenteric distant infiltration of ITCLD-GT to the neck lymph node in this patient. This is the first case of ITCLD-GT that has a definite distant lymph node invasion. ITCLD-GT usually has a relatively good prognosis but patients with ITCLD-GT may have abenteric distant infiltration. Thus, long-term follow-up and further study of the underlying mechanisms of this process are necessary.

Intestinal NK/T cell lymphoma: A case report

BACKGROUND

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

CASE SUMMARY

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

CONCLUSION

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

Post-transplant indolent T cell lymphoproliferative disorder in living donor liver transplantation: a case report

Background

Post-transplant lymphoproliferative disorder (PTLD) of T cell type has been rarely reported. Accurate diagnosis of this life-threatening rare form of PTLD is important for the treatment strategy.

Case presentation

A 7-year-old boy had severe diarrhea and weight loss progressively at 7 years post-living donor liver transplantation (LDLT) for biliary atresia. Endoscopy in the gastrointestinal (GI) tract revealed multiple erosions and ulcer lesions with prominent intraepithelial lymphocytosis in the duodenum and terminal ileum. Immunohistochemical examination demonstrated that these accumulated lymphocytes mainly comprised small- to medium-sized T cells expressing CD3, CD4, CD5, CD7, and CD103, but lacking CD8, CD56, and Epstein-Barr virus-encoded small RNAs. In addition, T cell receptor β gene rearrangement was detected by polymerase chain reaction analysis. Comprehensively, the lesions were best interpreted as post-transplant indolent T cell lymphoproliferative disorder (LPD) of the intestine. Clinical remission was achieved by reducing the immunosuppressant.

Conclusion

A rarely reported indolent type of T cell LPD in post-LDLT was diagnosed by direct inspection and histological investigation. Although the histological classification and therapeutic strategy for post-transplant indolent T cell LPD have not been established, reducing immunosuppression allowed complete remission in our case. To prevent the incidence of PTLD and de novo malignancy, developing a methodology to set a proper dose of immunosuppressant is required.

Peripheral T-cell lymphoma with gastrointestinal involvement and indolent T-lymphoproliferative disorders of the gastrointestinal tract

The 2017 WHO classification includes a new provisional entity of indolent T-lymphoproliferative disorders of the gastrointestinal tract (ITLPD-GIT). We investigated GI involvement of peripheral T-cell lymphoma (PTCL). Eighty-two patients were diagnosed with PTCL during 2007-2017. Eleven patients (13 %) had histologically-confirmed GI tract involvement {3 monomorphic epitheliotropic intestinal lymphoma (MEITL), 3 extranodal NK-/T-cell lymphoma nasal type (ENKL), 2 PTCL, not otherwise specified, 1 adult T-cell leukemia-lymphoma, 2 ITLPD-GIT}. Three patients each had lesions in the small intestine and multiple lesions, two each in the stomach and colon, and one in the duodenum. Six of the 11 patients remained alive. No perforation/stenosis was observed after chemo-radiotherapy, although one patient with ENKL developed gastric bleeding during chemotherapy. One patient with ITLPD-GIT (CD4^-/CD8⁺/Ki67^Low) with a colonic lesion showing diffuse edema and multiple aphtha by endoscope and diarrhea, initially diagnosed with MEITL, had active but stable disease after various chemotherapies for 1 year and no therapy for the next 5 years. Another patient with ITLPD-GIT (CD4⁺/CD8⁺/Ki67^Low) with a localized gastric lesion and slight epigastralgia was in remission for 1 year after radiation. In conclusion, about 10 % of PTCLs were complicated by GI tract lesions and most had a poor prognosis. ITLPD-GIT should be considered as a differential diagnosis based on histology and clinical course. Local complications after chemo/radiotherapy in PTCL with GI involvement were not frequent.

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.

Indolent T-Cell Lymphoproliferative Disorder of the Uterine Corpus: A Case Report

Primary lymphoproliferative disorders of the uterus are rare, with the majority being B-cell diseases or aggressive T-cell disease. We present the case of a 31-yr old in whom an Indolent T-cell lymphoproliferative disorder (iTCLPD) was identified in resection chippings for a suspected fibroid, following presentation with menorrhagia. Laboratory investigations revealed an oligoclonal T-cell infiltrate with the immunophenotype of nonactivated cytotoxic T cells, and a proliferative fraction of 10% to 15%. There was no clinical or radiologic evidence of systemic disease, and the patient remained well with no indication of relapse 1 yr from resection and diagnosis. iTCLPD of the uterine corpus has features in common with the recently described iTCLPD of the gastrointestinal tract and primary cutaneous acral CD8 T-cell lymphoma. Recognition of these parallels is important as few other cases of iTCLPD have been described, and it suggests local resection rather than systemic treatment as the best therapeutic strategy.

Genetic and phenotypic characterization of indolent T-cell lymphoproliferative disorders of the gastrointestinal tract

Indolent T-cell lymphoproliferative disorders of the gastrointestinal tract are rare clonal T-cell diseases that more commonly occur in the intestines and have a protracted clinical course. Different immunophenotypic subsets have been described, but the molecular pathogenesis and cell of origin of these lymphocytic proliferations is poorly understood. Hence, we performed targeted next-generation sequencing and comprehensive immunophenotypic analysis of ten indolent T-cell lymphoproliferative disorders of the gastrointestinal tract, which comprised CD4⁺ (n=4), CD8⁺ (n=4), CD4⁺/CD8⁺ (n=1) and CD4^-/CD8^- (n=1) cases. Genetic alterations, including recurrent mutations and novel rearrangements, were identified in 8/10 (80%) of these lymphoproliferative disorders. The CD4⁺, CD4⁺/CD8⁺, and CD4^-/CD8^- cases harbored frequent alterations of JAK-STAT pathway genes (5/6, 82%); STAT3 mutations (n=3), SOCS1 deletion (n=1) and STAT3-JAK2 rearrangement (n=1), and 4/6 (67%) had concomitant mutations in epigenetic modifier genes (TET2, DNMT3A, KMT2D). Conversely, 2/4 (50%) of the CD8⁺ cases exhibited structural alterations involving the 3' untranslated region of the IL2 gene. Longitudinal genetic analysis revealed stable mutational profiles in 4/5 (80%) cases and acquisition of mutations in one case was a harbinger of disease transformation. The CD4⁺ and CD4⁺/CD8⁺ lymphoproliferative disorders displayed heterogeneous Th1 (T-bet⁺), Th2 (GATA3⁺) or hybrid Th1/Th2 (T-bet⁺/GATA3⁺) profiles, while the majority of CD8⁺ disorders and the CD4^-/CD8^- disease showed a type-2 polarized (GATA3⁺) effector T-cell (Tc2) phenotype. Additionally, CD103 expression was noted in 2/4 CD8⁺ cases. Our findings provide insights into the pathogenetic bases of indolent T-cell lymphoproliferative disorders of the gastrointestinal tract and confirm the heterogeneous nature of these diseases. Detection of shared and distinct genetic alterations of the JAK-STAT pathway in certain immunophenotypic subsets warrants further mechanistic studies to determine whether therapeutic targeting of this signaling cascade is efficacious for a proportion of patients with these recalcitrant diseases.

Endoscopic and clinicopathological characteristics of gastrointestinal adult T-cell leukemia/lymphoma

Background

Adult T-cell leukemia/lymphoma (ATLL) frequently involves the gastrointestinal (GI) tract, and patients mainly show an aggressive clinical course despite of intensive cytotoxic treatments. We investigated the characteristic clinicopathological and endoscopic features of GI ATLL.

Methods

This was a retrospective analysis of 61 GI tract lesions in 54 ATLL patients.

Results

Thirty-six (67%) patients were classified as having lymphoma-type ATLL and 18 (33%) patients were classified as having acute-type with leukemic changes. Examined ATLL lesions in the stomach and intestine (small intestine and colorectum) were 40 (66%) and 21 (34%), respectively. Gastric ATLL lesions were frequently found in the lymphoma-type (29/38; 76%) compared with the acute-type lesions (11/23; 48%; P=0.023). Intestinal ATLL lesions were frequent in the acute-type (12/23; 52%) compared with the lymphoma-type lesions (9/38; 24%; P=0.023). Endoscopically, tumor-forming type lesions were significantly more frequent in lymphoma-type ATLL lesions (29/38 lesions; 76%) compared with acute-type lesions (10/23; 44%; P=0.0096). The superficial spreading-type was significantly more frequent in acute-type lesions (12/23 lesions; 52%) compared with lymphoma-type lesions (3/38; 8%; P=0.0003). Additionally, gastropathy-, enteropathy-, or proctocolitis-like lesions were distinct features, mainly in the acute type (9/23 lesions; 39%). Twenty three of 39 tumor-forming-type lesions (59%) were significantly composed of pleomorphic or anaplastic large cell lymphoma, and 13 of 15 superficial spreading-type lesions (87%) were significantly composed of pleomorphic medium-sized cells (P=0.007, in each). Six patients (11%) who were estimated as having primary GI ATLL based on restricted clinical stages, showed a significantly better overall survival (OS) compared with the 48 advanced-stage patients (P=0.017). Twenty patients with solitary tumor-forming-type lesions showed a significantly better OS than 17 patients with the multiple tumor-forming-type (P=0.015) and five with the mucosal-thickening-type lesions (P=0.04). Twenty-six patients with pleomorphic or anaplastic large cell ATLL showed a significantly better prognosis compared with 28 patients with pleomorphic medium-sized ATLL (P=0.034).

Conclusions

ATLL predominantly involves the stomach. Leukemic behavior of ATLL had a large influence on the tumor location and endoscopic features of GI tract lesions. Gastropathy-, enteropathy-, and proctocolitis-like lesions showed additional distinct characteristics. Primary GI ATLL in the early clinical stages, solitary tumor-forming-type lesions and large tumor cells showed better prognostic factors than other factors, respectively.

New/Revised Entities in Gastrointestinal Lymphoproliferative Disorders

The gastrointestinal tract is a common extranodal site of involvement by lymphomas. These may be diagnostically challenging because they can mimic a variety of benign conditions and may be difficult to subclassify when malignant. The classification of gastrointestinal lymphomas is an evolving area with some recent changes. Although some of these entities are rare, they are important to recognize because of the variable clinical presentations, comorbidities, and treatment implications. This article explores new and revised entities in gastrointestinal lymphoproliferative disorders.

Indolent T cell lymphoproliferative disorder with villous atrophy in small intestine diagnosed by single-balloon enteroscopy

Chronic diarrhea is one of the major symptoms in gastroenterology. However, this may be caused by pathologic conditions for which the diagnosis is critical. Villous atrophy, as an endoscopic lesion, accompanied by chronic diarrhea can occasionally be observed in the patients with inflammatory diseases of the gastrointestinal (GI) tract. Herein, we present a case with persistent diarrhea accompanied by intestinal wall thickening without any other significant endoscopic features other than villous atrophy in the jejunum and the ileum, where we diagnosed as an indolent T cell lymphoproliferative disorder (T-LPD) of the GI tract, defined in the 2016–2017 revised World Health Organization classification, via single-balloon enteroscopy (SBE). Interestingly, we found the same lymphocyte infiltration from the distal third portion of the duodenum, where gastroscopy could not reach, via SBE, even though no endoscopic findings were observed such as villous atrophy. Since infiltrating cells in the intestinal tissues were CCR4⁺, mogamulizumab was administered with resulting durable symptomatic remission for more than 2 years. Patients with persistent diarrhea may have serious small intestinal disorder including not only chronic inflammatory diseases but also lymphoid neoplasmic conditions including T-LPD of GI tract.

Epidemiology and Pathology of T- and NK-Cell Lymphomas

PURPOSE

This review will describe and update readers on the recent changes in the 2017 WHO classification regarding peripheral T-cell lymphomas.

RECENT FINDINGS

Signficant advances in molecular studies have resulted in revisions to the classification as well as introduction to provisional entities such as breast implant-associated ALCL and nodal PTCL with T-follicular helper phenotype.

SUMMARY

Major advances in molecular and gene expression profiling has expanded our knowledge of these rare and aggressive diseases.

An unusual case report of indolent T-cell lymphoproliferative disorder with aberrant CD20 expression involving the gastrointestinal tract and bone marrow

Background

Indolent T-cell proliferative disorder of the GIT is a rare and provisional entity in the revised WHO 2016 classification. The patients usually have prolonged survival with persistent disease even without any treatment.

Case presentation

The 46 years old male patient has been followed up for more than 6 years without chemotherapy. Repeated gastrointestinal biopsies showed expansion of the lamina propria extending to the submucosa by small to medium sized lymphocytes with minimal cytologic atypia. The lymphoid cells were positive for CD3, CD43, TIA-1, CD2, CD7 and the B-cell marker CD20; but negative for CD4, CD8, PAX5, CD56, cyclinD1, granzyme (GraB) and Epstein Barr virus-encoded RNA (EBER). Ki-67(MIB1) index was less than 10%. Molecular tests demonstrated a clonal rearrangement for T-cell receptor γ (TCR γ) gene but immunoglobulin chain (IgH, IgK, IgL) gene remained germline. Recognition of possible aberrant CD20 expression in indolent T-cell LPD is important to avoid potential diagnostic pitfall and improper treatment.

Conclusions

We present an unusual case of indolent T-cell lymphoproliferative disorder with aberrant CD20 expression, Recognition of this unusual immunophenotype of indolent T-cell LPD of GI helps to eschew misdiagnosis of B-cell and other high grade lymphomas and inappropriate aggressive treatment.

Feline low-grade alimentary lymphoma: an emerging entity and a potential animal model for human disease

BACKGROUND

Low-grade alimentary lymphoma (LGAL) is characterised by the infiltration of neoplastic T-lymphocytes, typically in the small intestine. The incidence of LGAL has increased over the last ten years and it is now the most frequent digestive neoplasia in cats and comprises 60 to 75% of gastrointestinal lymphoma cases. Given that LGAL shares common clinical, paraclinical and ultrasonographic features with inflammatory bowel diseases, establishing a diagnosis is challenging. A review was designed to summarise current knowledge of the pathogenesis, diagnosis, prognosis and treatment of feline LGAL. Electronic searches of PubMed and Science Direct were carried out without date or language restrictions.

RESULTS

A total of 176 peer-reviewed documents were identified and most of which were published in the last twenty years. 130 studies were found from the veterinary literature and 46 from the human medicine literature. Heterogeneity of study designs and outcome measures made meta-analysis inappropriate. The pathophysiology of feline LGAL still needs to be elucidated, not least the putative roles of infectious agents, environmental factors as well as genetic events. The most common therapeutic strategy is combination treatment with prednisolone and chlorambucil, and prolonged remission can often be achieved. Developments in immunohistochemical analysis and clonality testing have improved the confidence of clinicians in obtaining a correct diagnosis between LGAL and IBD. The condition shares similarities with some diseases in humans, especially human indolent T-cell lymphoproliferative disorder of the gastrointestinal tract.

CONCLUSIONS

The pathophysiology of feline LGAL still needs to be elucidated and prospective studies as well as standardisation of therapeutic strategies are needed. A combination of conventional histopathology and immunohistochemistry remains the current gold-standard test, but clinicians should be cautious about reclassifying cats previously diagnosed with IBD to lymphoma on the basis of clonality testing. Importantly, feline LGAL could be considered to be a potential animal model for indolent digestive T-cell lymphoproliferative disorder, a rare condition in human medicine.

Immunohistochemical Profiling of Canine Intestinal T-Cell Lymphomas

Human enteropathy-associated T-cell lymphoma (EATL) is classified into 2 distinct subgroups based on their phenotypes (type I and type II). Canine intestinal T-cell lymphoma can be morphologically classified into large and small cell lymphomas (LCL and SCL, respectively). Their association with human EATL or immunohistochemical and biological features has not been well characterized. In this study, the immunohistochemical profiles of 17 cases of LCL and 33 cases of SCL were evaluated with markers used for human EATL classification. Morphologically, LCL was characterized by sheet-like proliferation of large to moderately sized neoplastic lymphocytes, with scant clear cytoplasm and pleomorphic, irregularly shaped nuclei containing distinctive nucleoli and scattered chromatin. In contrast, SCL was characterized by the proliferation of monomorphic small neoplastic lymphocytes, accompanied by infiltration of nonneoplastic plasma cells. Interestingly, 8 cases demonstrated mixed LCL and SCL morphologies. Granular cytoplasmic expression of granzyme B was observed in most LCL and SCL cases. Membranous expression of CD56 was demonstrated in only 2 of 17 LCL and 0 of 33 SCL cases. Coexpression of CD20 by neoplastic T cells was observed in more SCL cases (16/33; 48%) than LCL cases (1/17; 6%). The CD56-positive cells in 2 cases were negative for CD20. Although canine LCL shares common features with human EATL type I, canine SCL cells and human EATL type II differ in their immunophenotype. Canine intestinal T-cell lymphoma had a homogeneous immunophenotype regardless of cell morphology. The findings of this study may indicate large cell transformation of SCL rather than 2 distinct entities.

Relationship of the mucosal microbiota to gastrointestinal inflammation and small cell intestinal lymphoma in cats

Background

The gastrointestinal (GI) microbiota in healthy cats is altered in IBD. Little research has been performed to identify whether specific bacterial groups are associated with small cell GI lymphoma (LSA).

Hypothesis

Mucosal bacteria, including Enterobacteriaceae and Fusobacterium spp., are abundant in intestinal biopsies of cats with small cell GI LSA compared to cats with IBD.

Animals

Fourteen cats with IBD and 14 cats with small cell GI LSA.

Methods

Retrospective case control study. A search of the medical records was performed to identify cats diagnosed with IBD and with GI LSA. Bacterial groups identified by FISH in GI biopsies were compared between cohorts and correlated to CD11b⁺ and NF‐κB expression.

Results

Fusobacterium spp. (median; IQR bacteria/region) were higher in cats with small cell GI LSA in ileal (527; 455.5 – 661.5; P = .046) and colonic (404.5; 328.8 – 455.5; P = .016) adherent mucus, and combined colonic compartments (free mucus, adherent mucus, attaching to epithelium) (8; 0 – 336; P = .017) compared to cats with IBD (ileum: 67; 31.5 – 259; colon: 142.5; 82.3 – 434.5; combined: 3; 0 – 34). Bacteroides spp. were higher in ileal adherent mucus (P = .036) and 3 combined ileal compartments (P = .034) of cats with small cell GI LSA. There were significant correlations between Fusobacterium spp. totals and CD11b⁺ cell (P = .009; rs .476) and NF‐κB expression (P = .004; rs .523).

Conclusions

The bacterial alterations appreciated might be influential in development of small cell GI LSA, and should drive further studies to elucidate the effects of microbial‐mediated inflammation on GI cancer progression.