Primary follicular lymphoma of the small intestine: alpha4beta7 expression and immunoglobulin configuration suggest an origin from local antigen-experienced B cells

Bridging clinicopathologic features and genetics in follicular lymphoma: Towards enhanced diagnostic accuracy and subtype differentiation

Follicular lymphoma (FL) is a neoplasm that originates from germinal center B cells and typically forms at least a partial follicular pattern. Approximately 85% of FL cases harbor the t(14;18)(q32;q21)/IGH::BCL2 which leads to the overexpression of BCL2. These cases are referred to as classic FL in the current World Health Organization classification [1]. These neoplasms often exhibit hallmark epigenetic deregulation due to recurrent mutations in genes such as KMT2D, CREBBP, and EZH2, with KMT2D and CREBBP considered founding events in FL lymphomagenesis. In contrast, about 15% of FL cases are negative for the t(14;18), which could present diagnostic challenges. These cases may lack the typical genetic markers and require careful pathological and molecular analysis for accurate diagnosis. This review aims to provide an up-to-date pathology resource on FL, focusing on the pathological and molecular characteristics of these neoplasms. We will detail the diagnostic criteria for FL and emphasize the importance of genetic and mutational analyses in accurately characterizing and distinguishing FL subtypes. Furthermore, we will propose methodologies and best practices for the diagnostic work-up of FL to enhance diagnostic accuracy.

Clinical characteristics and outcomes of Brazilian patients with duodenal-type follicular lymphoma: a multicenter retrospective study

Duodenal-type follicular lymphoma (DFL) is a rare subtype classified by the 5th edition of the WHO and international consensus classifications of lymphoid neoplasms, typically presenting as localized disease with favorable outcomes. This multicenter retrospective study examines 53 Brazilian DFL patients with a median age of 58.2 years (33-85), with males comprising 50% (n = 27). According to Lugano GI tract classification, 40 patients (75%) were stage I. Median follow-up was 2.9 years (range 0.1-11). Incidental diagnosis occurred in 28 patients (52.8%) during routine endoscopy; 24 patients (45%) presented mild gastrointestinal symptoms. Treatments included watchful waiting (32 patients, 60.4%), rituximab monotherapy (15 patients, 28.3%), radiotherapy (three patients, 5.7%), and chemoimmunotherapy (three patients, 5.7%). Three patients experienced disease progression; watchful waiting showed three spontaneous remissions. No deaths occurred during follow-up. This study, the first from Latin America, demonstrates a good prognosis across treatments, highlighting Watchful waiting's effectiveness.

Duodenal-type follicular lymphoma in 18F-FDG PET/CT imaging: a case report

Follicular lymphoma (FL) is a subtype of non-Hodgkin lymphoma (NHL) that is typically characterized by a slow-growing course. Duodenal-type follicular lymphoma (D-FL) was recently reclassified as a distinct variant. This subtype exhibits unique clinical and biological characteristics, which set it apart from other forms of FL. We report a case of a 36-year-old male patient with multiple, small, gray polypoid lesions in the descending duodenum which were detected by esophagogastroduodenoscopy. The pathological diagnosis was low-grade D-FL. 18F-FDG PET/CT was performed for staging and revealed the pancreas and peripheral lymph nodes were involved by FL, with a clinical IV stage. The patient underwent a bone marrow smear cytology, which revealed no bone marrow abnormalities, and excluded bone marrow involvement. He was treated with six cycles of chemotherapy using the R-CHOP regimen and reached complete remission.

Duodenal-type follicular lymphoma more than 10 years after treatment intervention: A retrospective single-center analysis

BACKGROUND

Duodenal-type follicular lymphoma (D-FL) has been recognized as a rare entity that accounts for approximately 4% of primary gastrointestinal lymphomas. D-FL follows an indolent clinical course compared with common nodal FL and is generally considered to have a better prognosis. Therefore, the "watch and wait" approach is frequently adopted as the treatment method. Alternatively, there is an option to actively intervene in D-FL. However, the long-term outcomes of such cases are poorly understood.

AIM

To clarify the clinical outcomes after long-term follow-up in cases of D-FL with treatment intervention.

METHODS

We retrospectively analyzed patients who met the following criteria: the lesion was confirmed by endoscopy, the diagnosis of D-FL was confirmed histopathologically, and the patient was followed-up for more than 10 years after the intervention at our center.

RESULTS

We identified 5 cases of D-FL. Two patients showed a small amount of bone marrow involvement (Stage IV). Rituximab was used as a treatment for remission in all 5 patients. It was also used in combination with chemotherapy in 2 Stage IV patients as well as for maintenance treatment. Radiation therapy was performed in 2 cases, which was followed by complete remission (CR). Eventually, all 5 patients achieved CR and survived for more than 10 years. However, 3 patients experienced recurrence. One patient achieved a second CR by retreatment, and in another case, the lesion showed spontaneous disappearance. The remaining patient had systemic widespread recurrence 13 years after the first CR. Biopsy results suggested that the FL lesions were transformed into diffuse large B-cell lymphoma. The patient died 4 years later despite receiving various chemotherapies.

CONCLUSION

In this study, the treatment for patients of D-FL in Stage IV was successful. In the future, criteria for how to treat "advanced" D-FL should be established based on additional cases. This study of patients with D-FL indicates that whole-body follow-up examinations should continue for a long time due to a fatal recurrence 13 years after reaching CR.

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.

Scientific Advances and the Evolution of Diagnosis, Subclassification and Treatment of Lymphoma

The diagnosis of lymphoma has evolved tremendously over time. Initially, diagnosis of lymphoma was largely based on morphology alone. Over time, immunophenotyping using flow cytometry and immunohistochemistry, and then in situ hybridization, have contributed dramatically to the pathologist's ability to recognize, diagnose and subclassify lymphomas more precisely. In recent years, cytogenetic and molecular genetic techniques have developed that allow evaluation of abnormalities in lymphomas, leading to an understanding of their pathogenesis and opening the door to targeted therapies that will lead to better outcomes for lymphoma patients.

What do we know about duodenal-type follicular lymphoma? From pathological definition to treatment options

Duodenal-type follicular lymphoma (DFL) is a newly recognised variant of follicular lymphoma (FL), although little is known about its biology and clinical evolution. In general, patients tend to have mild symptoms and do not require therapy, comparable with other forms of low-tumour burden asymptomatic FL. Specific pathological features, such as a dendritic cell meshwork, low expression of CD10 and upregulation of activation-induced cytidine deaminase can help the diagnosis. The molecular landscape of DFL is similar to the classical nodal presentation of FL, although studies using gene expression profiling demonstrate a close relation with MALT lymphomas. Markers associated with inflammation have suggested that the microenvironment plays a likely role in the pathogenesis of DFL and its low progression rate. Clinical series published vary between 20-63 patients with an estimated overall survival between 92-100% and a median follow-up ranging between 20 and 107 months. Treatment options include a watch and wait strategy, rituximab monotherapy and radiotherapy. In this review, we summarise current pathological data and treatment studies in DFL.

Early Events in Lymphoid Neoplasms and Indolent Follicular Lymphomas

Technical advances in diagnostic modalities have led to the characterization of indolent lymphoid disorders similar to the in situ lesions described in epithelial malignancies. These early and indolent lymphoid lesions share clinicopathologic characteristics with well-characterized lymphoid malignancies such as chronic lymphocytic leukemia and follicular lymphoma. The in situ lesions have an indolent clinical course with only a minor subset shown to progress to frank malignancies. In addition to the in situ lesions, new indolent lymphoproliferative disorders have been recently characterized. Diagnosis and characterization of these indolent lesions is necessary to prevent overtreatment with aggressive therapeutic regimens.

Ontogeny, Genetics, Molecular Biology, and Classification of B- and T-Cell Non-Hodgkin Lymphoma

Mature B- and T-cell lymphomas are diverse in their biology, etiology, genetics, clinical behavior, and response to specific therapies. Here, we review the principles of diagnostic classification for non-Hodgkin lymphomas, summarize the characteristic features of major entities, and place recent biological and molecular findings in the context of principles that are applicable across the spectrum of mature lymphoid cancers.

Colorectal follicular lymphoma: A case report

RATIONALE

Considering the low incidence of colorectal follicular lymphoma (FL) and its clinical features in endoscopic views, only a few studies have described the pathological diagnosis and treatment of this disease. This study aimed to reveal the overall process of clinical diagnosis and treatment of colorectal FL by conducting a case review.

PATIENT CONCERNS

A 27-year-old female presented to our department because of "severe bloody stool" lasting for more than 1 month. Her primary symptom was melena. Colonoscopy revealed widespread flat polyps with various immunophenotypes (CD10+, BCL2+, BCL6+, cyclin D1-, CD5-) in the colorectal area.

DIAGNOSIS

In accordance with manifestations on positron emission tomography-computed tomography (PET/CT), the patient was diagnosed with stage IV colorectal FL.

INTERVENTIONS

PET/CT reexamination after 2 courses of rituximab, cyclophosphamide, liposomal doxorubicin, vincristine sulfate, and hydroprednisone (R-CHOP) regimen and 3 courses of R-CHOP plus etoposide regimen for chemotherapy indicated a significant reduction in tumor burden. Subsequently, rituximab was administered alone in 2 treatment courses.

OUTCOMES

Lesions on PET/CT disappeared after reexamination. No recurrence was observed within the 12-month follow-up period.

LESSONS

Colorectal FL is a rare disease with an inert clinical course and is common in the ileocecal area. Endoscopic views show multiple polyps. Interventional treatment is usually provided after observation of clinical symptoms or during disease progression. The disease has a relatively good prognosis.

Primary small bowel lymphoma presenting as invagination

One of the causes of invagination in adults is primary small bowel lymphoma. Primary small bowel lymphomas are rare, present themselves with complications due to diagnostic difficulties, and are diagnosed only after surgical intervention. In case of invagination, one of the complications of these tumors, namely primary small bowel lymphoma, should also be considered as a cause in the diagnosis. In this paper, the diagnosis and therapy of a rare case of primary polypoid-type small intestinal lymphoma demonstrating findings of obstruction due to invagination have been presented and discussed in the light of the literature.

Duodenal-type and nodal follicular lymphomas differ by their immune microenvironment rather than their mutation profiles

The mutational landscape of DTFL is highly related to nodal FL but harbors fewer multiple/biallelic mutations in KMT2D. The immune microenvironment of DTFL is distinct from nodal FL and characterized by a chronic inflammation gene signature.

Radiation Therapy Outcome and Clinical Features of Duodenal-Type Follicular Lymphoma

PURPOSE

Duodenal-type follicular lymphoma (FL) is a rare variant of FL. There is still no consensus on the initial treatment, and clinical features including endoscopic findings are not familiar to most physicians. The objective of this study was to evaluate the outcome of patients who were initially treated with radiation therapy for duodenal-type FL.

Materials and Methods

We retrospectively analyzed 20 patients who were consecutively diagnosed with duodenaltype FL between 2008 and 2017. All patients received radiation therapywith curative intent.

RESULTS

The median age of the patients was 52 years (range, 26 to 66 years), and females were predominant. Most patients (n=18, 90%) had stage I disease, and were diagnosed by a regular health examination in an asymptomatic state. The histological grade was one in 19 patients (95%), and the endoscopic findings were diffuse nodular (n=8), whitish granular (n=8), and mixed pattern (n=4). Radiation therapy was delivered to 17 patients with 24 Gy in 12 fractions, and to three patients with 30.6-36 Gy in 18 fractions. All patients were evaluated with endoscopy for response to radiation therapy, and complete response was achieved in 19 patients (95%). At the time of analysis, all patients survived without any evidence of late toxicities related with radiation therapy.

CONCLUSION

Taken together, radiation therapy alone could be effective in controlling duodenal lesion. A further study with longer follow-up duration is warranted to confirm our findings.

Gastric follicular lymphoma: A report of 3 cases and a review of the literature

Follicular lymphoma (FL) occurs primarily in the gastrointestinal tract, with the stomach being one of the rarest sites. According to the literature, <20 cases of primary gastric FL have been reported, with the number of cases with detailed pathological descriptions being even less. The aim of the present study was to compare clinicopathological features of gastric FL with FL at alternative sites. A total of 3 cases of gastric FL were retrieved from among 3,216 cases in the databases of 4 university hospitals in South Korea: Seoul National University (SNU) Hospital, SNU Boramae Hospital, SNU Bundang Hospital (all Seoul, South Korea) and Dongtan Sacred Heart Hospital Hallym University (Dongtan, South Korea), including 2 primary cases and 1 case that was possibly secondary to nodal FL. The 2 primary gastric FL cases were incidentally detected in routine health check-ups. An endoscopy revealed a single polypoid submucosal mass and biopsies failed to confirm the diagnosis due to minimal mucosal involvement. Therefore, a partial gastrectomy was performed. The epicenters of the tumors were submucosal, with focal extension to the muscularis propria. However, 1 case exhibited an isolated FL nodule in the omentum. Histopathological examination revealed FL of grade 1–2 with a follicular pattern and with strong expression of germinal center markers and B-cell lymphoma 2 (BCL2). Rearrangement of BCL2 was not identified using fluorescence in situ hybridization studies in 2 cases. In contrast to these 2 cases, the remaining FL case was confirmed with an endoscopic biopsy. The endoscopy revealed multiple eroded polypoid lesions, and pathology revealed FL of grade 1–2 with a predominantly diffuse pattern, and with immunoglobulin heavy chain IGH/BCL2 translocation. In view of the extensive lymphadenopathy, the last case possibly presented as secondary involvement of nodal FL. It is challenging to diagnose FL in the stomach due to little mucosal involvement, as well as the unfamiliarity of the tumor due to its rarity. However, the results of the present study suggest that primary gastric FL may exhibit unique pathological features, including a predominantly follicular pattern and an absence of BCL2 rearrangement.

Successful Clarithromycin Monotherapy in a Patient with Primary Follicular Lymphoma of the Duodenum

Primary follicular lymphoma of the duodenum (FL-D) constitutes a rare subtype of extranodal follicular lymphoma with a usually indolent course. To date, no distinct treatment recommendations have been defined for those patients. We report the case of a 58-year-old male patient presenting with endoscopically assessed, symptomatic FL-D who was treated with clarithromycin monotherapy in analogy to recent data for mucosa-associated lymphoid tissue lymphoma. Each treatment cycle consisted of clarithromycin 500 mg twice daily for 3 weeks followed by a 2-week break. After four cycles of treatment, the patient showed a very good response with normal macroscopic findings confirmed by endosonographic examination and only focal minimal residual disease of lymphoma persisting in the histological assessment. The patient is currently asymptomatic and without treatment for 24+ months. As clarithromycin combines antimicrobial and direct antiproliferative effects mediated through a variety of pleiotropic mechanisms, this appears to be an interesting treatment approach for indolent lymphoma, particularly in those where a chronic infectious background cannot be completely ruled out, i.e., gastrointestinal manifestations. We suggest further investigation of this treatment approach.

CD38 expression on paraffin sections distinguishes follicular lymphoma from reactive follicular hyperplasia

This study explored the utility of CD38 immunodetection in paraffin-embedded tissue sections for differentiating follicular lymphoma (FL) from reactive follicular hyperplasia (RFH) by examining RFH (n = 47) and FL (n = 178). In RFH specimens, uniform weak-to-moderate CD38 immunostaining was observed in centrocytes and centroblasts across germinal centers (GCs). Moreover, these specimens contained a subset of strongly CD38-positive cells predominantly located in the light zone, which may represent antigen-selected surviving centrocytes that are committed to differentiate into plasma cells, i.e., centrocytoid plasma cells (CPCs). In FL specimens, CD38 staining yielded two patterns. In pattern I (146 specimens), weak-to-moderate CD38 staining was observed in tumor cells within neoplastic follicles. Neoplastic follicles in 126 of the 146 specimens did not contain strongly CD38-positive CPCs. Furthermore, individual neoplastic follicles in the remaining 20 FL specimens contained very few strongly CD38-positive cells (which may represent normal residual CPCs). In pattern II (32 cases), neoplastic follicles exhibited loss of CD38 expression accompanied by disappearance of CPCs. In conclusion, compared with RFH, the decrease of strongly CD38-positive CPCs in neoplastic follicles was a striking alteration, reflecting blocks in the lymphoid differentiation pathway. Moreover, loss of CD38 expression in neoplastic GC B-cells in some FL specimens can serve as an immunophenotypic characteristic of FL.

Primary duodenal follicular lymphoma with late disseminated nodal relapse responsive to rituximab monotherapy: A case report

Gastrointestinal follicular lymphoma is a rare malignancy accounting for only 1-3.6% of primary non-Hodgkin lymphomas of the gastrointestinal tract and it is a relatively new clinical entity that was recently classified as a distinct variant of systemic follicular lymphoma. Therefore, data regarding long-term outcome are currently lacking. In addition, a consensus on the management of this disease has not been established and treatment strategies are derived from systemic follicular lymphoma. We herein report the case of a 51-year-old female patient diagnosed with duodenal follicular lymphoma who had nodal relapse nearly 5 years after complete remission. The patient was successfully treated with a 4-week course of rituximab during the initial diagnosis and relapse. To the best of our knowledge, this is the first case report to demonstrate the efficacy of a 4-week course of rituximab during both the initial diagnosis and nodal relapse. The aim of this report was to add to the limited available data on the treatment of gastrointestinal follicular lymphoma.

Anti-leukemic activity of microRNA-26a in a chronic lymphocytic leukemia mouse model

Dysregulation of microRNAs (miRNAs) plays an important role in the pathogenesis of chronic lymphocytic leukemia (CLL). The Eμ-TCL1 transgenic mouse develops a form of leukemia that is similar to the aggressive type of human B-CLL, and this valuable model has been widely used for testing novel therapeutic approaches. Here, we adopted this model to investigate the potential effects of miR-26a, miR-130an and antimiR-155 in CLL therapy. Improved delivery of miRNA molecules into CLL cells was obtained by developing a novel system based on lipid nanoparticles conjugated with an anti-CD38 monoclonal antibody. This methodology has proven to be highly effective in delivering miRNA molecules into leukemic cells. Short- and long-term experiments showed that miR-26a, miR-130a and anti-miR-155 increased apoptosis after in vitro and in vivo treatment. Of this miRNA panel, miR-26a was the most effective in reducing leukemic cell expansion. Following long-term treatment, apoptosis was readily detectable by analyzing cleavage of PARP and caspase-7. These effects could be directly attributed to miR-26a, as confirmed by significant downregulation of its proven targets, namely cyclin-dependent kinase 6 and Mcl1. The results of this study are relevant to two distinct areas. The first is related to the design of a technical strategy and to the selection of CD38 as a molecular target on CLL cells, both consenting efficient and specific intracellular transfer of miRNA. The original scientific finding inferred from the above approach is that miR-26a can elicit in vivo anti-leukemic activities mediated by increased apoptosis.

Gastrointestinal follicular lymphoma: using primary site as a predictor of survival

Gastrointestinal follicular lymphoma (GI-FL) is a rare extranodal variant of follicular lymphoma (FL) that has been increasingly reported in the literature. An especially indolent course is linked to the disease after a lack of observed patient death in past studies. However, overall survival (OS) and associated prognostic factors remain unclear. A large population-based database was utilized to identify demographic and clinicopathologic characteristics of GI-FL, along with survival differences among primary sites. The Surveillance, Epidemiology, and End Results Registry was used to identify GI-FL cases between the years of 1973 and 2012. Kaplan-Meier curves compared OS differences and Cox proportional hazard models analyzed prognostic factors. Final analysis included 1109 cases. Small intestinal cases, which included those with single-site and multi-segment involvement, were most common (63.6%) followed by gastric (18.2%) and colorectal cases (18.2%). Small intestinal GI-FL presented more frequently with grade I histology, and less often with grade III histology (P < 0.001 and P < 0.001, respectively). Small intestinal cases had better outcomes (5-year OS = 80.9%, P < 0.001) compared to cases involving the stomach (5-year OS = 52.7%) and colorectum (5-year OS = 71.5%). On multivariate analysis for predictors of mortality, small intestinal involvement predicted for better survival; hazard ratio (HR) 0.66 (95% CI: 0.51-0.85). Advanced age (≥66), grade (grade III), and stage (Ann Arbor Stage III/IV) predicted for mortality with HR 5.46 (95% CI: 3.80-7.84), 1.42 (95% CI: 1.10-1.83), 1.57 (95% CI: 1.15-2.16), respectively. GI-FL has poorer outcomes than previously suggested. Small intestinal involvement has a better prognosis. A possible biological basis for this will require further investigations in the future.

Radiation therapy for localized duodenal low-grade follicular lymphoma

The aim of this study was to evaluate the initial treatment results and toxicities of radiation therapy for patients with early stage low-grade follicular lymphoma (FL) arising from the duodenum. We reviewed 21 consecutive patients with early stage duodenal FL treated with radiation therapy between January 2005 and December 2013 at the Cancer Institute Hospital, Tokyo. The characteristics of patients were: median age 62 years (range, 46-79 years), gender (male, 6; female, 15), clinical stage (I, 20; II1, 1), histological grade (I, 17; II, 4). All patients were treated with radiation therapy alone. The median radiation dose was 30.6 Gy (range, 30.6-39.6) in 17 fractions. The involved-site radiation therapy was delivered to the whole duodenum. The median follow-up time was 43.2 months (range 21.4-109.3). The 3-year overall survival (OS), relapse-free survival (RFS) and local control (LC) rates were 94.7%, 79.3% and 100%, respectively. There were four relapses documented outside the treated volumes: two in the gastrointestinal tract (jejunum, terminal ileum), one in an abdominal lymph node (mesenteric lymph node) and one in the bone marrow. None died of the disease; one death was due to acute myeloid leukemia. No toxicities greater than Grade 1 were observed during treatment and over the follow-up time. The 30.6 Gy of involved-site radiation therapy provided excellent local control with very low toxicities. Radiation therapy could be an effective and safe treatment option for patients with localized low grade FL arising from the duodenum.

Primary Follicular Lymphoma of the Gastrointestinal Tract: Case Report and Review

PURPOSE

Primary gastrointestinal follicular lymphoma (GI-FL) is considered a rare disease with fewer than 400 cases reported in the literature. It accounts for roughly 1-3 % of GI non-Hodgkins lymphomas (NHL). It originates in the GI tract and typically affects small bowel. The disease has an indolent course, and a prolonged survival can be expected in most cases. Due to its rarity, an optimal diagnostic work up and treatment plan has not been well established.

METHODS

Endoscopic evaluation of the entire gastrointestinal (GI) tract using esophagogastroduodenoscopy (EGD), wireless capsule endoscopy, double-balloon enteroscopy, colonoscopy, and whole body examination with fluorodeoxyglucose-positron emission tomography (FDG-PET) has been suggested to more accurately stage the disease and guide the treatment plan.

RESULTS

Treatment options for GI follicular lymphoma include watch and wait strategy, surgery, chemotherapy, radiation, immuno-radiotherapy, or a combination of these modalities.

CONCLUSION

In this article, we have summarized the existing information regarding clinical presentation, diagnostic evaluation, and treatment options for this rare entity after presenting a case of GI-FL who was diagnosed during an EGD for evaluation of belching, heartburn, and weight loss.

Recent advances in intestinal lymphomas

A large variety of lymphoma types may develop as primary intestinal neoplasms in the small intestines or, less often, in the colorectum. Among these are a few entities such as enteropathy-associated T-cell lymphoma or immunoproliferative small intestinal disease that, essentially, do not arise elsewhere than in the gastrointestinal tract. In most instances the primary intestinal lymphomas belong to entities that also occur in lymph nodes or other mucosal sites, and may show some peculiar features. In the case of follicular lymphoma, important differences exist between the classical nodal cases and the intestinal cases, considered as a variant of the disease. It is likely that the local intestinal mucosal microenvironment is a determinant in influencing the pathobiological features of the disease. In this review we will present an update on the clinical, pathological and molecular features of the lymphoid neoplasms that most commonly involve the intestines, incorporating recent developments with respect to their pathobiology and classification. We will emphasize and discuss the major differential diagnostic problems encountered in practice, including the benign reactive or atypical lymphoid hyperplasias, indolent lymphoproliferative disorders of T or natural killer (NK) cells, and Epstein-Barr virus (EBV)-related lymphoproliferations.

Early lymphoid lesions: conceptual, diagnostic and clinical challenges

There are no "benign lymphomas", a fact due to the nature of lymphoid cells to circulate and home as part of their normal function. Thus, benign clonal expansions of lymphocytes are only rarely recognized when localized. Recent studies have identified a number of lymphoid proliferations that lie at the interface between benign and malignant. Some of these are clonal proliferations that carry many of the molecular hallmarks of their malignant counterparts, such as BCL2/IGH and CCND1/IGH translocations associated with the in situ forms of follicular lymphoma and mantle cell lymphoma, respectively. There are other clonal B-cell proliferations with low risk of progression; these include the pediatric variants of follicular lymphoma and marginal zone lymphoma. Historically, early or incipient forms of T/NK-cell neoplasia also have been identified, such as lymphomatoid papulosis and refractory celiac disease. More recently an indolent form of T-cell lymphoproliferative disease affecting the gastrointestinal tract has been described. Usually, CD8(+), the clonal cells are confined to the mucosa. The clinical course is chronic, but non-progressive. NK-cell enteropathy is a clinically similar condition, composed of cytologically atypical NK-cells that may involve the stomach, small bowel or colon. Breast implant-associated anaplastic large cell lymphoma is a cytologically alarming lesion that is self-limited if confined to the seroma cavity. Atypical lymphoid proliferations that lie at the border of benign and malignant can serve as instructive models of lymphomagenesis. It is also critical that they be correctly diagnosed to avoid unnecessary and potentially harmful therapy.

Duodenal follicular lymphoma: comprehensive gene expression analysis with insights into pathogenesis

Follicular lymphoma (FL) of the gastrointestinal tract, particularly duodenal follicular lymphoma (DFL), is a rare variant of FL with indolent clinical behavior, and this disease is included in the 2008 World Health Organization classification system. In contrast to nodal follicular lymphoma (NFL), DFL occurs most frequently in the second part of the duodenum, lacks follicular dendritic cell meshworks and has memory B-cell characteristics. However, its molecular pathogenesis is still unclear. In the present study, we examined 10 DFL, 18 NFL and 10 gastric MALT lymphoma samples using gene expression analysis. Quantitative RT-PCR experiments and immunohistochemical analysis for 72 formalin-fixed, paraffin-embedded tissues from an independent series, including 32 DFL, 19 gastric MALT lymphoma and 27 NFL samples, were performed for validation of microarray data. Gene expression profiles of the three lymphoma types were compared using 2918 differentially expressed genes (DEG) and results suggested that DFL shares characteristics of MALT lymphoma. Among these DEG, CCL20 and MAdCAM-1 were upregulated in DFL and MALT but downregulated in NFL. In contrast, protocadherin gamma subfamily genes were upregulated in DFL and NFL. Quantitative RT-PCR and immunohistochemical studies demonstrated concordant results. Double immunofluorescence studies revealed that CCL20 and CCR6 were co-expressed in both DFL and MALT. We hypothesize that increased expression of CCL20 and MAdCAM-1 and co-expression of CCL20 and CCR6 may play an important role in tumorigenesis.

Nature and importance of follicular lymphoma precursors

It is now widely recognized that cancer development is a protracted process requiring the stepwise acquisition of multiple oncogenic events. In humans, this process can take decades, if not a lifetime, blurring the notion of 'healthy' individuals. Follicular lymphoma exemplifies this multistep pathway of oncogenesis. In recent years, variants of follicular lymphoma have been recognized that appear to represent clonal B-cell expansions at an early stage of follicular lymphoma lymphomagenesis. These include follicular lymphoma in situ, duodenal follicular lymphoma, partial involvement by follicular lymphoma, and in the blood circulating follicular lymphoma-like B cells. Recent genetic studies have identified similarities and differences between the early lesions and overt follicular lymphoma, providing important information for understanding their biological evolution. The data indicate that there is already genomic instability at these early stages, even in instances with a low risk for clinical progression. The overexpression of BCL2 in t(14;18)-positive B cells puts them at risk for subsequent genetic aberrations when they re-enter the germinal center and are exposed to the influences of activation-induced cytidine deaminase and somatic hypermutations. The emerging data provide a rationale for clinical management and, in the future, may identify genetic risk factors that warrant early therapeutic intervention.

Early lesions of follicular lymphoma: a genetic perspective

The pathogenesis of follicular lymphoma is a multi-hit process progressing over many years through the accumulation of numerous genetic alterations. Besides the hallmark t(14;18), it is still unclear which other oncogenic hits contribute to the early steps of transformation and in which precursor stages these occur. To address this issue, we performed high-resolution comparative genomic hybridization microarrays on laser-capture micro-dissected cases of follicular lymphoma in situ (n=4), partial involvement by follicular lymphoma (n=4), and duodenal follicular lymphoma (n=4), assumed to represent, potentially, the earliest stages in the evolution of follicular lymphoma. Cases of reactive follicular hyperplasia (n=2), uninvolved areas from follicular lymphoma in situ lymph nodes, follicular lymphoma grade 1-2 (n=5) and follicular lymphoma grade 3A (n=5) were used as controls. Surprisingly, alterations involving several relevant (onco)genes were found in all entities, but at significantly lower proportions than in overt follicular lymphoma. While the number of alterations clearly assigns all these entities as precursors, the pattern of partial involvement by follicular lymphoma alterations was quantitatively and qualitatively closer to that of follicular lymphoma, indicating significant selective pressure in line with its faster rate of progression. Among the most notable alterations, we observed and validated deletions of 1p36 and gains of the 7p and 12q chromosomes and related oncogenes, which include some of the most recurrent oncogenic alterations in overt follicular lymphoma (TNFRSF14, EZH2, MLL2). By further delineating distinctive and hierarchical molecular and genetic features of early follicular lymphoma entities, our analysis underlines the importance of applying appropriate criteria for the differential diagnosis. It also provides a first set of candidates likely to be involved in the cascade of hits that pave the path of the various progression phases to follicular lymphoma development.

Duodenal follicular lymphoma lacks AID but expresses BACH2 and has memory B-cell characteristics

We have reported previously that duodenal follicular lymphoma (FL) is distinct from nodal FL and showed more resemblance to mucosa-associated lymphoid tissue lymphoma, and that FL frequently involved the duodenal second portion. In the present study, we examined duodenal FLs and gastric/colonic FLs to clarify the clinicopathological and immunological differences between the tumor types. We analyzed 8 samples of gastric FL, 17 of duodenal ones, and 5 of colonic/rectal ones, and characterized them by immunohistochemistry, immunogenotyping, and histology. Gastric and colonic FLs presented in submucosal to subserosal areas, whereas duodenal ones presented in the mucosal to submucosal layers. Immunohistochemical analysis revealed that duodenal FLs exhibited the following phenotypes: CD10 (+), B-cell lymphoma 2 (BCL-2) (+), BCL-6 (+), activation-induced cytidine deaminase (AID) (-), BACH2 (+), CD27 (+), MUM-1 (-), Blimp-1 (-), and loose CD21 network (duodenal pattern). Gastric/colonic FLs exhibited the following phenotypes: CD10 (+), BCL-2 (+), BCL-6 (+), AID (+), BACH2 (+), CD27 (-), MUM-1 (-), Blimp-1 (-), and a dense CD21 network (nodal pattern). Expression of AID and CD27 in lymphoma cells and the CD21 network pattern were considerably different between duodenal FLs and gastric/colonic ones. Moreover, in situ hybridization revealed that, in the duodenal FLs, BACH2 was expressed at the periphery of the tumor follicle and tumor villi. The number of immunoglobulin heavy-chain variable domains VH4 and VH5 were higher in duodenal follicular lymphomoas than in gastric FLs. The lymphoma cells of duodenal FLs are different from those of gastric/colonic FLs, and duodenal FL is distinct even within the gastrointestinal tract. Somatic hypermutation in immunoglobulin genes and CD27 expression are hallmarks of memory B cells. We suggest that duodenal FL cells are in the memory B-cell stage, and require BACH2 instead of AID for ongoing mutation.

Extranodal and splenic small B-cell lymphoma

Although almost any non-Hodgkin lymphoma can involve the spleen or an extranodal site as part of more widely disseminated disease, there is a group of small B-cell lymphomas that specifically arise in these locations. These are important to recognise as some appear to have a behaviour and prognosis that is distinct from their nodal counterparts. In addition, there are entities that are specific to extranodal locations (such as extranodal marginal zone lymphoma) and to the red or white pulp of the spleen. In this review, the characteristics of these entities will be presented as well as clues to help distinguish lymphoma from reactive infiltrates in extranodal sites and measure to distinguish between small B-cell lymphomas encountered in the spleen and at extranodal locations.

Gastrointestinal B-cell lymphomas: From understanding B-cell physiology to classification and molecular pathology

The gut is the most common extranodal site where lymphomas arise. Although all histological lymphoma types may develop in the gut, small and large B-cell lymphomas predominate. The sometimes unexpected finding of a lymphoid lesion in an endoscopic biopsy of the gut may challenge both the clinician (who is not always familiar with lymphoma pathogenesis) and the pathologist (who will often be hampered in his/her diagnostic skill by the limited amount of available tissue). Moreover, the past 2 decades have spawned an avalanche of new data that encompasses both the function of the reactive B-cell as well as the pathogenic pathways that lead to its neoplastic counterpart, the B-cell lymphoma. Therefore, this review aims to offer clinicians an overview of B-cell lymphomas in the gut, and their pertinent molecular features that have led to new insights regarding lymphomagenesis. It addresses the question as how to incorporate all presently available information on normal and neoplastic B-cell differentiation, and how this knowledge can be applied in daily clinical practice (e.g., diagnostic tools, prognostic biomarkers or therapeutic targets) to optimalise the managment of this heterogeneous group of neoplasms.

Diagnosis and management of rare gastrointestinal lymphomas

Primary gastrointestinal (GI) lymphoma is rare, however accounts for 30-40% of cases of extranodal lymphoma. Several lymphoma subtypes have a propensity for GI tract involvement. Whilst the literature is dominated by data related to the more common extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) and diffuse large B-cell lymphoma (DLBCL) of the stomach, this review focuses on the rare subtypes of enteropathy-associated T-cell lymphoma (EATL), GI follicular lymphoma, mantle cell lymphoma (lymphomatous polyposis coli) and extranodal natural killer (NK)/T-cell lymphoma nasal-type (ENKTL). Due to its rarity, the majority of data regarding primary GI lymphoma have been derived from subgroups of larger cohorts. Clinical characteristics, prognosis and management can differ from those of nodal disease, despite corresponding histology. We discuss these differences and the challenges associated with diagnosis and management of these rare diseases.

Lymphoproliferative disorders of the gastrointestinal tract: a review and pragmatic guide to diagnosis

CONTEXT

The gastrointestinal tract is the most common site of extranodal lymphomas. Although all histologic categories of malignant lymphoma develop in the gastrointestinal tract, large B-cell lymphomas predominate, followed by extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT) type; the latter is especially prevalent in stomach. The acceptance of extranodal marginal zone lymphoma of MALT type as a clinicopathologic entity has reduced the number of cases that formerly were interpreted as florid lymphoid hyperplasia ("pseudolymphoma"). Nonetheless, the distinction of lymphoid hyperplasia from a lymphoma of MALT type in small biopsy specimens remains problematic.

OBJECTIVE

To assess the relevant morphologic, immunologic, molecular, and genetic properties of gastrointestinal lymphomas and to present a feasible tactic for diagnosis, expressly for small biopsy specimens.

DATA SOURCES

Case-derived material and literature review using PubMed (National Library of Medicine).

CONCLUSIONS

Most gastrointestinal lymphomas are readily amenable to an unqualified diagnosis, primarily those cases consisting of monomorphic large cells whether of B- or T-cell lineage, including cases associated with enteropathy. Diagnosis for infiltrates dominated by small lymphocytes remains taxing, as the differential diagnosis embraces not only MALT lymphoma and lymphoid hyperplasia but also mantle cell lymphoma, follicular lymphoma, and chronic lymphocytic leukemia/small lymphocytic lymphoma. Adherence to strict morphologic criteria is the standard for diagnosis, but these criteria should be augmented by immunologic studies together with judicious use of molecular techniques to determine clonality. In establishing a diagnosis of gastric marginal zone lymphoma of MALT type, determination of t(11;18)(q21;q21) status may be required since this translocation has clinical ramifications.

Primary follicular lymphoma of the duodenum is a distinct mucosal/submucosal variant of follicular lymphoma: a retrospective study of 63 cases

PURPOSE

Small series with limited follow-up have suggested primary follicular lymphoma of the duodenum (FL-D) to be an indolent disease. We report our experience on a large series of patients followed for a median time period of longer than 6 years.

PATIENTS AND METHODS

The study comprised 63 patients with primary FL-D defined as stage I disease. Endoscopy and detailed pathologic work-up was performed at diagnosis and at restaging to monitor the behavior of the neoplastic process.

RESULTS

Histologically, all 63 patients had FL, low grade (1 to 2). Duodenal endosonography demonstrated lesions confined to mucosa/submucosa in 19 of 20 patients. At an overall median follow-up of 77 months (range, 12 to 177 months), only two untreated patients had developed nodal disease, the remaining 61 patients never experienced extrasmall intestinal disease and large cell transformation did not occur at all. Among 24 patients followed by watch and wait strategy, seven showed spontaneous complete regression and 17 had stable disease; radiotherapy resulted in complete regression in all 19 patients; anti-CD20 antibody monotherapy achieved complete regression in four patients and stable disease in one patient. Various chemotherapy protocols in eight patients caused complete regression in all of them, but local relapses occurred in three. No patients required surgery or died of disease.

CONCLUSION

These findings characterize primary FL-D as a remarkably indolent FL variant, which, even left untreated, does not develop tumorous growth, very rarely disseminates (two of 63 patients) and does not transform to high grade disease. A watch and wait approach appears to be the most sensible strategy.

Recent Advances in Follicular Lymphoma: Pediatric, Extranodal, and Follicular Lymphoma in Situ

Follicular lymphoma is a relatively common B-cell lymphoma composed of follicle center B lymphocytes. Follicular lymphomas occurring in the pediatric population and in some extranodal sites exhibit particular clinicopathologic features and clinical behavior that are often distinct from adult nodal follicular lymphoma. A type of "in-situ" follicular lymphoma presents as intrafollicular neoplastic cells in a background of architecturally normal lymphoid tissue and may be difficult to recognize in routine sections. Accurate recognition of the morphologic variants and clinicopathologic subtypes of follicular lymphoma is important to avoid confusing them with other lymphomas and reactive processes; in addition, some of these subtypes of follicular lymphoma display unusually indolent clinical behavior that warrant their separation from "conventional" follicular lymphoma.

Gastrointestinal follicular lymphoma: review of the literature

Gastrointestinal follicular lymphoma (GI-FL) is a relatively rare disease, accounting for only 1%-3.6% of gastrointestinal non-Hodgkin's lymphoma. Although the duodenum and terminal ileum are considered to be the most common sites of origin, the development of wireless capsule endoscopy and double-balloon enteroscopy has increased the detection of GI-FL in every part of the small intestine. Approximately 70% of patients with GI-FL are estimated to have multiple lesions throughout the entire gastrointestinal tract. FL is a low-grade lymphoma that usually develops very slowly. If the lymphoma causes no symptoms, immediate treatment may not be necessary. Standard therapy has not yet been established for GI-FL, but chemotherapy, radiotherapy, monoclonal antibody therapy, or a combination of these therapies, is sometimes performed based on the therapeutic regimens for nodal FL. Regimens including conventional chemotherapy with rituximab, which achieve high response rates in nodal FL, are commonly used for GI-FL. The long-term clinical outcome of GI-FL is unclear. The results of a few series on the long-term outcomes of patients with GI-FL treated with conventional therapy indicate a median relapse-free time ranging from 31 to 45 months. On the other hand, in patients with GI-FL who were followed without treatment, the median time to disease progression was 37.5 months. Thus, whether to initiate aggressive therapy or whether to continue watchful waiting in patients with GI-FL is a critically important decision. Ongoing research on biomarkers to guide individualized GI-FL therapy may provide invaluable information that will lead to the establishment of a standard therapeutic regimen.

Non-Hodgkin's lymphoma revealed by an ilio-colic intussusception in a Moroccan patient: a case report

Intussusceptions are rare but well-known causes of the small bowel obstruction in adults and an underlying cause is present in the majority of cases. Lymphoma's involvement of the ileum is one of the rare causes of intussusception. CT is a sensitive examination that diagnoses intussusceptions and provides an excellent pre-operative evaluation including possible extension and dissemination especially in intestinal lymphomas. The treatment is almost always surgical and the pathological study is needed for diagnostic confirmation. Authors present an unusual case of intestinal intussusception due to lymphoma of the terminal part of the ileum in a 49-year-old man. Computed tomography confirmed the diagnosis of intussusception and non-Hodgkin's lymphoma of B-cell was diagnosed by histological examination after surgical treatment. Primary intestinal lymphomas differ from gastric lymphomas in clinical features, treatment, and prognosis. They are not well characterized and the standardized concepts for their clinical diagnosis and management are absent. The aim of this rare observation is to shed light on NHL of the small bowel, its clinical and radiological diagnosis and its treatment especially in forms revealed by intussusceptions in adults.

Determining the expression rate of the IgM and IgA in B cell lymphomas by immunohistochemistry

This study aimed at assessing the expression rate of IgA and IgM in B cell lymphoma immunohistochemically. Paraffin-embedded specimens of NHL evaluated for presence of CD20 by immunohistochemical staining and then, the positive cases were again immunohistochemically assessed for expression of IgM and IgA. Fifty two paraffin-embedded specimens evaluated. Thirty six cases (69.2%) were positive for the CD20. The mean age of these patients (CD20+ cases) was 50.0 +/- 23.6 years. Twenty two cases (61%) were male and 14 cases (39%) were female. The frequency of the IgM+, IgA+ and IgA/IgM+ (simultaneous) cases was 15 (41.7%), 9 (25%) and 4 (11.1%), respectively. The current rates are in the range of similar reports in the literature.

Double-balloon endoscopy depicts diminutive small bowel lesions in gastrointestinal lymphoma

The aim was to determine the prevalence of small bowel involvement in patients with gastrointestinal (GI) lymphoma by double-balloon endoscopy (DBE). We examined 29 patients with primary GI lymphoma by oral and anal DBEs. Clinicopathologic features related to the prevalence of diminutive small bowel involvement and the clinical outcome were retrospectively investigated. Diminutive small bowel lesions were found in 14 patients. The prevalence of the lesions was not different between patients with primary small bowel lymphoma and those with primary extra-small bowel lymphoma (50% versus 47%, P = 0.6). However, clinical stage was more advanced in patients with the lesions than in those without (P < 0.05). The lesions were more frequently found in T-cell lymphoma (100%) and follicular lymphoma (77%) than in the other types of lymphoma (15%) (P < 0.05). Diminutive small intestinal lesions occur in patients with GI lymphoma, especially in those with follicular lymphoma and T-cell lymphoma. GI lymphomas of these histologic types are candidates for scrutiny by DBE.

Colonic involvement in a patient with chronic lymphocytic leukaemia

Various gastrointestinal infiltrations have been described in patients with chronic lymphocytic leukaemia (CLL). Here, we report a 69-year-old man with CLL and anaemia in whom the macroscopic finding of colonoscopy was normal, but the histological specimens revealed lymphocytic leukemia in ileum and in colon. If a CLL patient has any symptoms suggesting a possible GI manifestation of the haematologic disease or anaemia not explained by bone marrow infiltration or hemolysis, the diagnostic evaluation should include endoscopies with adequate biopsies.

Chronic inflammatory disease, lymphoid tissue neogenesis and extranodal marginal zone B-cell lymphomas

Chronic autoimmune or pathogen-induced immune reactions resulting in lymphoid neogenesis are associated with development of malignant lymphomas, mostly extranodal marginal zone B-cell lymphomas (MZBCLs). In this review we address (i) chemokines and adhesion molecules involved in lymphoid neogenesis; (ii) the autoimmune diseases and pathogens which are associated with development of B-cell lymphomas; (iii) the molecular mechanisms involved in the initiation and progression of MZBCL; and (iv) 'potential' mouse models for MZBCL.

Duodenal and nodal follicular lymphomas are distinct: the former lacks activation-induced cytidine deaminase and follicular dendritic cells despite ongoing somatic hypermutations

Although most follicular lymphomas are believed to be of nodal origin, they sometimes originate from the duodenum. We have reported that the latter differ from nodal follicular lymphomas in having lower clinical stages and uniformly low histological grades, along with variable region of immunoglobulin heavy chain gene (VH) usage that is more similar to mucosa-associated lymphoid tissue (MALT) lymphomas. Little is known, however, about whether they possess other characteristics of nodal follicular lymphomas, particularly ongoing mutations with follicular dendritic cells. We examined 17 cases for which PCR identified the monoclonal bands of the immunoglobulin gene. The duodenal cases showed ongoing mutations, but they lacked activation-induced cytidine deaminase (AID) expression, a statistically significant difference from the nodal cases (P<0.001), and their follicular dendritic cell networks were disrupted. Moreover, not only were VH deviations observed but also they used very restricted VH genes. Although the mechanisms of ongoing mutation without AID and follicular dendritic cell were not clarified, restricted VH usage strongly suggested that antigen stimulation was involved, and that was similar to MALT lymphomas. In conclusion, duodenal follicular lymphomas were shown to be unique, in that they had ongoing hypermutations such as nodal cases, but the mechanisms involved in the hypermutation were quite different; furthermore, restricted VH usage suggested a strong similarity to the antigen-dependent origin of MALT lymphomas.

Classification of lymphoid neoplasms: the microscope as a tool for disease discovery

In the past 50 years, we have witnessed explosive growth in the understanding of normal and neoplastic lymphoid cells. B-cell, T-cell, and natural killer (NK)-cell neoplasms in many respects recapitulate normal stages of lymphoid cell differentiation and function, so that they can be to some extent classified according to the corresponding normal stage. Likewise, the molecular mechanisms involved the pathogenesis of lymphomas and lymphoid leukemias are often based on the physiology of the lymphoid cells, capitalizing on deregulated normal physiology by harnessing the promoters of genes essential for lymphocyte function. The clinical manifestations of lymphomas likewise reflect the normal function of lymphoid cells in vivo. The multiparameter approach to classification adopted by the World Health Organization (WHO) classification has been validated in international studies as being highly reproducible, and enhancing the interpretation of clinical and translational studies. In addition, accurate and precise classification of disease entities facilitates the discovery of the molecular basis of lymphoid neoplasms in the basic science laboratory.