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

A large colonic polyp: an atypical presentation of follicular lymphoma

Follicular lymphoma of the gastrointestinal tract is a rare entity accounting for <7% of all non-Hodgkin lymphomas and is more common in the small intestine, whereas colorectal manifestations account for only 1%-2% of the cases. Most patients have limited disease with promising overall survival in comparison to nodal lymphoma although the morphologic, immunophenotypic, and genetic aspects of nodal follicular lymphomas remain the same. Despite the lack of randomized clinical trials, chemotherapy is frequently used to treat NCCN grade III and IV colonic follicular lymphomas with favorable prognosis. We hereby present a case of follicular lymphoma of the colon that was treated conservatively with a successful outcome.

Duodenal-type follicular lymphoma: comprehensive insights into disease characteristics and established treatment strategies

PURPOSE OF REVIEW

This review aims to detail the characteristics and outcomes of duodenal-type follicular lymphoma (DTFL), a rare lymphoma variant. It focuses on integrating recent reports in treatment modalities and highlights emerging insights into the unique biological features of the disease.

RECENT FINDING

Recent studies confirm the indolent nature of DTFL, with extended follow-up periods showing favorable outcomes under watchful waiting strategies and a notable proportion of patients experiencing spontaneous remission. Additionally, advancements in understanding the disease's biology revealed that the tumor microenvironment is marked by specific genomic expressions indicative of chronic inflammation.

SUMMARY

The observations of spontaneous resolution and the generally favorable progression of DTFL call for a conservative approach in initiating treatment. Clinical management should judiciously consider the disease's typically benign course against the potential risks of intervention, promoting customized treatment protocols tailored for cases with clinical necessity. Additionally, the discovery of an inflammatory tumor microenvironment and molecular evidence suggesting an antigen-driven process highlight critical areas for future research.

[Studies on clinicopathological features of duodenal-type follicular lymphoma of 18 patients]

To investigate the clinical and pathological characteristics of duodenal-type follicular lymphoma (D-FL), and to deepen the understanding of Duodenal-type follicular lymphoma. The clinical symptoms, endoscopic features, pathologic features, immunophenotype, molecular pathological features and treatment follow-up of 18 D-FL patients diagnosed in Department of Pathology, Beijing Tiantan Hospital affiliated to Capital Medical University between January 2020 and July 2023 were summarized. A total of 18 patients with D-FL were included, including 10 males and 8 females. The median age was 49 (32-69) years respectively. Most of the patients were found during gastroenteroscopy or presented with the common gastrointestinal symptoms of stomach pain, acid reflux, vomiting and diarrhea. Most endoscopic findings were multiple small gray and white polyposis. In the pathological morphology, the mucous layer and submucous layer showed lymphoid follicular structures with full and strained follicles. The immunophenotype showed that the tumor cells strongly expressed CD20 and BCL2 and had low proliferation activity. Immunoglobulin clonal analysis of 1 case showed IgK monoclonal rearrangement (1/1). FISH showed 1 case of BCL2 gene rearrangement (1/3). All patients did not receive targeted chemotherapy and adopted a wait-and-see strategy. Median follow-up was 12 (2-34) months. This study shows that D-FL is an indolent lymphoma, which tends to occur in the duodenum and has a good prognosis.

Frequent CDKN2B/P15 and DAPK1 methylation in duodenal follicular lymphoma is related to duodenal reactive lymphoid hyperplasia

Duodenal type follicular lymphoma (DFL), a rare entity of follicular lymphoma (FL), is clinically indolent and is characterized by a low histological grade compared with nodal follicular lymphoma (NFL). Our previous reports revealed that DFL shares characteristics of both NFL and mucosa-associated lymphoid tissue (MALT) lymphoma in terms of clinical and biological aspects, suggesting its pathogenesis may involve antigenic stimulation. In contrast to NFL, the genomic methylation status of DFL is still challenging. Here, we determined the methylation profiles of DNAs from patients with DFL (n = 12), NFL (n = 10), duodenal reactive lymphoid hyperplasia (D-RLH) (n = 7), nodal reactive lymphoid hyperplasia (N-RLH) (n = 5), and duodenal samples from normal subjects (NDU) (n = 5) using methylation specific PCR of targets previously identified in MALT lymphoma (CDKN2B/P15, CDKN2A/P16, CDKN2C/P18, MGMT, hMLH-1, TP73, DAPK, HCAD). DAPK1 was frequently methylated in DFL (9/12; 75%), NFL (9/10; 90%), and D-RLH (5/7; 71%). CDKN2B/P15 sequences were methylated in six DFL samples and in only one NFL sample. Immunohistochemical analysis showed that p15 expression inversely correlated with methylation status. Genes encoding other cyclin-dependent kinase inhibitors (CDKN2A/P16, CDKN2C/P18) were not methylated in DFL samples. Methylation of the genes of interest was not detected in DNAs from D-RLH, except for DAPK1, and the difference in the extent of methylation between NDU and D-RLH was statistically significant (P = 0.013). Our results suggest that D-RLH serves as a reservoir for the development of DFL and that methylation of CDKN2B/P15 plays an important role in this process.

Disease surveillance evaluation of primary small-bowel follicular lymphoma using capsule endoscopy images based on a deep convolutional neural network (with video)

BACKGROUND AND AIMS

Capsule endoscopy (CE) is useful in evaluating disease surveillance for primary small-bowel follicular lymphoma (FL), but some cases are difficult to evaluate objectively. This study evaluated the usefulness of a deep convolutional neural network (CNN) system using CE images for disease surveillance of primary small-bowel FL.

METHODS

We enrolled 26 consecutive patients with primary small-bowel FL diagnosed between January 2011 and January 2021 who underwent CE before and after a watch-and-wait strategy or chemotherapy. Disease surveillance by the CNN system was evaluated by the percentage of FL-detected images among all CE images of the small-bowel mucosa.

RESULTS

Eighteen cases (69%) were managed with a watch-and-wait approach, and 8 cases (31%) were treated with chemotherapy. Among the 18 cases managed with the watch-and-wait approach, the outcome of lesion evaluation by the CNN system was almost the same in 13 cases (72%), aggravation in 4 (22%), and improvement in 1 (6%). Among the 8 cases treated with chemotherapy, the outcome of lesion evaluation by the CNN system was improvement in 5 cases (63%), almost the same in 2 (25%), and aggravation in 1 (12%). The physician and CNN system reported similar results regarding disease surveillance evaluation in 23 of 26 cases (88%), whereas a discrepancy between the 2 was found in the remaining 3 cases (12%), attributed to poor small-bowel cleansing level.

CONCLUSIONS

Disease surveillance evaluation of primary small-bowel FL using CE images by the developed CNN system was useful under the condition of excellent small-bowel cleansing level.

Pathogenesis of Gastrointestinal Follicular Lymphomas: Consideration Based on Histopathology and Endoscopic Findings

Gastrointestinal (GI) follicular lymphoma (FL) is the most frequently diagnosed extranodal FL; however, its pathogenesis is debatable. We investigated the distribution, endoscopic, and histopathologic findings of 366 GI FL samples obtained from 298 patients. FLs were most frequently observed in the small intestine (71%), including the duodenum (52%), but were also commonly found in the stomach (15%) and colon (12%). The proportion of granular lesions in the duodenum, terminal ileum, colon, and stomach was 74%, 39%, 24%, and 0%, respectively. Submucosal or ulcerated tumors were frequently observed in the stomach (48%) and colon (52%). Most GI FL showed grade 1 to 2 histology (89%) as well as CD10 + (93%) and BCL2 + (98%) positivity. There were no significant differences in the endoscopic or histologic findings between primary and secondary GI FLs. As known, the mucosa of the small intestine is thin and villous, while the mucosa of the stomach and colon is thicker and has a smooth surface. Granular lesions corresponding to very small FL were detected in the former but rarely in the latter. Nine (7%) patients with primary GI FL developed histologic transformation to diffuse large B-cell lymphoma (n=8) or high-grade B-cell lymphoma (n=1) 10 months to 14 years after the diagnosis of FL. Two patients died of lymphoma. In conclusion, the incidence and endoscopic findings differed, but the histopathology was similar in FLs in each site. These differences might be attributed to variations in each GI site's mucosal structure and the neoplastic follicles' size. Due to its characteristic structure, very small classic FLs might be detectable mainly in the small intestine.

Clinicopathological and molecular genetic characteristics of primary gastric follicular lymphoma☆,☆☆,☆☆☆

Primary gastric follicular lymphomas (FLs) have been rarely reported and little is known about their characteristics. In the present study, we report five cases of primary gastric FL and describe their clinicopathological and molecular genetic features. A total of seven samples from five patients were investigated for clinicopathological characteristics and somatic mutations by the targeted sequencing of 50 lymphoma-related genes. Two cases were identified as slightly elevated submucosal tumors and three cases as polypoid tumors. Histologically, all cases were low-grade FLs. The immuno-profile was CD20⁺/CD10⁺/BCL2⁺ in four cases and CD20⁺/CD10⁺/BCL2^- in one case. Immunostaining pattern for CD21 was similar to that of classic FL. BCL2 rearrangement was not identified in fluorescence in situ hybridization studies in any of the five cases. NGS analysis showed mutations in genes involved in epigenetic modifications (KMT2D, ARID1A, EP300, CREBBP), NK-kB pathway (CARD11), and JAK-STAT pathway as found in classic follicular lymphoma. All cases presented with clinical I without the involvement of regional or systemic lymph nodes. Four patients were well, whereas one patient who received endoscopic mucosal resection of tumor without additional chemotherapy or radiotherapy experienced three relapses. In conclusion, primary gastric FL is characterized by a low-grade neoplasm with infrequent BCL2 rearrangement. After resection of the lesion, additional treatment such as radiation therapy or chemotherapy is required as there is a possibility of recurrence.

Predictive factors for the progression of primary localized stage small-bowel follicular lymphoma

BACKGROUND

Primary small-bowel follicular lymphoma (FL) is mainly diagnosed as a duodenal lesion during esophagogastroduodenoscopy. Recently, with the widespread use of small-bowel endoscopy, FL in the jejunum and ileum has been detected. Most patients with small-bowel FL are diagnosed at the localized stage, and a watch-and-wait policy is used. However, the predictive factors for the progression of small-bowel FL have not been clarified. This study retrospectively examined the predictive factors for the progression of primary localized stage small-bowel FL based on clinicopathological and endoscopic findings.

METHODS

We enrolled 60 consecutive patients with primary small-bowel FL diagnosed at two tertiary hospitals between January 2005 and December 2020, with localized stage, low grade, and low tumor burden with the watch-and-wait policy. We examined the predictive factors for progression according to the clinicopathological and endoscopic findings. Endoscopic findings were focused on the color tone, circumferential location of follicular lesions (circumference ≥ 1/2 or < 1/2), fusion of follicular lesions (fusion [ +] or [ -]), and protruded lesions (≥ 6 mm or < 6 mm).

RESULTS

Progressive disease was observed in 12 (20%) patients (mean observation period, 76.4 ± 55.4 months). In the multivariate analysis, "circumference ≥ 1/2" and "fusion (+)" were significant predictive factors for progression. According to the Kaplan-Meier analysis, progression-free survival was significantly shorter in the "circumference ≥ 1/2" and/or "fusion (+)" group than in the "circumference < 1/2" and "fusion ( -)" group.

CONCLUSIONS

Endoscopic findings of "circumference ≥ 1/2" and "fusion (+)" were significant predictive factors for the progression of primary localized stage small-bowel FL.

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.

Development of diffuse large B-cell lymphoma from duodenal type follicular lymphoma: a retrospective study of 23 cases

The incidence and clinical characteristics of histological transformation (HT) from duodenal type follicular lymphoma (DFL) are unclear. A retrospective analysis was conducted to identify the incidence and clinical features of HT from DFL in 23 cases with DFL. The median follow-up duration was 4.6 years (range, 0.8-20 years). HT to diffuse large B-cell lymphoma was observed in 2 of 23 cases during follow-up (8.7%). One of two cases transformed at 21 months later with increased serum lactate dehydrogenase (LDH; 1655 U/L) and abdominal lymphadenopathy. Partial response was achieved after R-THP (pirarubicin)-COP therapy, but the disease progressed. The other case transformed at 8.3 years with an increase of serum LDH (4022 U/L), abdominal lymphadenopathy, and bone marrow involvement. The disease was refractory to DA-EPOCH-R and a high-dose methotrexate/cytarabine regimen. The patient received allogenic peripheral blood stem cell transplantation and finally achieved complete response. Both cases developed HT at nodal or other intestinal lesions with no progression of the primary duodenal lesion. No significant factors for the occurrence of HT were identified. Although the incidence is low, HT could occur in DFL with aggressive clinical manifestations.

Density and size of lymphoid follicles are useful clues in differentiating primary intestinal follicular lymphoma from intestinal reactive lymphoid hyperplasia

Background

Primary intestinal follicular lymphoma (PI-FL) is a rare and indolent lymphoma and is challenging for diagnosis with endoscopic biopsy specimens. Whole slide imaging (WSI) has been increasingly used for assisting pathologic diagnosis, but not for lymphoma yet, probably because there are usually too many immunostained sections in a single case. In this study we attempted to identify morphological clues of PI-FL in the endoscopic biopsy specimens by measuring various parameters using WSI.

Methods

We retrospectively investigated 21 PI-FL cases, and scanned the HE sections from 17 of these cases with endoscopic biopsy specimens. Sections from 17 intestinal biopsies showing reactive lymphoid hyperplasia were scanned for comparison. The density and diameter of lymphoid follicles and the shortest distance of these follicles to the surface epithelia were measured on WSI. Comparisons of the aforementioned parameters were made between the neoplastic and reactive follicles.

Results

The density of follicles was significantly higher in PI-FL than that of reactive hyperplasia (median 0.5 vs. 0.2/mm²; p < 0.01). Furthermore, the neoplastic follicles were significantly larger (median diameter 756.9 vs. 479.7 μm; p < 0.01). The shortest distance of follicles to the surface epithelia tended to be closer in PI-FL (104.7 vs. 177.8 μm, p = 0.056), but not statistically significant.

Conclusions

In this study we found that in PI-FL the density and diameter of lymphoid follicles as measured from WSI were significantly different from that of intestinal reactive lymphoid hyperplasia. When facing the diagnostic challenge between these two entities in routine practice, pathologists might be alerted by these morphological clues and request for immunohistochemistry for differential diagnosis.

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.

Tumour-immune microenvironment in duodenal-type follicular lymphoma

Despite duodenal-type follicular lymphoma (DTFL) being morphologically, immunophenotypically and genetically indistinguishable from nodal FL (nFL), this entity typically shows a significantly better prognosis. Here, we analysed the tumour immune microenvironments of diagnostic specimens from patients with DTFL (n = 30), limited-stage FL (LSFL; n = 19) and advanced-stage FL (ASFL; n = 31). The mean number of CD8⁺ tumour-infiltrating lymphocytes (TILs) in the neoplastic follicles was higher in DTFL (1,827/mm² ) than in LSFL (1,150/mm² ) and ASFL (1,188/mm² ) (P = 0·002, P = 0·002, respectively). In addition, CD8⁺ PD1^-  T cells with non-exhausting phenotype were more abundant in the peripheral blood (PB) of DTFL than in LSFL and ASFL, indicating that DTFL may exhibit a better and longer-lasting T cell-mediated immune response. Moreover, whereas FOXP3⁺ CTLA-4⁺ effector regulatory T cells (eTregs) were rarely observed in the neoplastic follicles of DTFL (mean: 12/mm² ), they were more abundant in LSFL (78/mm² ) and ASFL (109/mm² ) (P = 2·80 × 10^-5 , P = 4·74 × 10^-8 , respectively), and the numbers of eTregs correlated inversely with those of CD8⁺ TILs (r = -0267; P = 0·018). Furthermore, DTFL showed significantly fewer circulating FOXP3^hi CD45RA^- CD25^hi eTregs (0·146%) than ASFL (0·497%) and healthy controls (0·639%) (P = 0·0003, P = 6·79 × 10^-7 , respectively). These results suggest that the augmented anti-tumour immune reactions may contribute to a better prognosis on DTFL.

Morphologic variant of follicular lymphoma reminiscent of hyaline-vascular Castleman disease

Follicular lymphoma (FL) with hyaline-vascular Castleman disease (FL-HVCD)-like features is a rare morphologic variant, with fewer than 20 cases in the literature. Herein, we report a case of FL-HVCD in a 37-year-old female who presented with isolated neck lymph node enlargement. The excised lymph node showed features reminiscent of HVCD, including regressed germinal centers (GCs) surrounded by onion skin-like mantle zones, lollipop lesions composed of hyalinized blood vessels penetrating into regressed GCs, and hyalinized interfollicular stroma. In addition, focal areas of abnormally conglomerated GCs composed of homogeneous, small centrocytes with strong BCL2, CD10, and BCL6 expression were observed, indicating partial involvement of the FL. Several other lymphoid follicles showed features of in situ follicular neoplasia. Based on the observations, a diagnosis of FL-HVCD was made. Although FLHVCD is very rare, the possibility of this variant should be considered in cases resembling CD. Identification of abnormal, neoplastic follicles and ancillary immunostaining are helpful for proper diagnosis.

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.

Duodenal-Type Follicular Lymphoma: A Clinicopathologic Review

Duodenal-type follicular lymphoma (D-FL) is a newly recognized entity in the 2016 World Health Organization classification update. It has an immunophenotype similar to that of other FLs and usually carries the typical t(14;18)(q32;q21) translocation. However, unlike other FLs, D-FL is almost always diagnosed at a low stage and stays localized to the small intestine, most commonly the second portion of the duodenum, whereas the vast majority of other FLs are diagnosed at an advanced stage. Additionally, D-FL gene expression and pathogenesis appear to be more closely related to extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue than to other types of FL. Therefore, many oncologists have opted to treat this variant of FL in a "watch and wait" manner because of its excellent prognosis and the rarity of D-FL to progress even when no treatments are attempted.

Watch-and-wait policy versus rituximab-combined chemotherapy in Japanese patients with intestinal follicular lymphoma

BACKGROUND AND AIM

Few reports have demonstrated the effectiveness of treatments for intestinal follicular lymphoma (FL) because of the limited number of patients who undergo comprehensive small intestinal examinations. This study compared the efficacy of rituximab-combined chemotherapy in patients with asymptomatic and low tumor burden (LTB) intestinal FL, according to the criteria of the Groupe d'Etude des Lymphomes Folliculaires, with that of a "watch and wait" (W&W) approach.

METHODS

The endoscopic examination for entire gastrointestinal tracts was performed in 29 Japanese patients with intestinal FL. These patients had CD21-positive follicular dendritic cells arranged in a duodenal pattern. In a prospective, two-center, open-label trial, this study evaluated the efficacy of rituximab-combined chemotherapy ([cyclophosphamide, doxorubicin, vincristine, and prednisone] or [cyclophosphamide, vincristine, and prednisone]) and prolonged treatment with rituximab (R-Chemo+prolongedR) in 14 patients and compared their outcomes with those of 15 patients managed with a W&W approach.

RESULTS

Four patients managed with the W&W plan showed worsening macroscopic findings, lesion area enlargement, or clinical stage progression but stayed on this plan because they had LTB and experienced no changes in bowel function. In the R-Chemo+prolongedR group, all patients achieved complete remission; recurrence occurred in one patient, who was subsequently managed with the W&W plan because of LTB. There were no significant differences in progression-free survival between the two groups (P = 0.1045). Overall survival was 100% in both groups.

CONCLUSIONS

The prognoses of patients with asymptomatic intestinal FL and LTB who were managed with a W&W strategy were comparable with those of patients receiving R-Chemo+prolongedR.

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.

The degree of overlap between the follicular dendritic cell meshwork and tumor cells in mantle cell lymphoma is associated with prognosis

This study concerning mantle cell lymphoma (MCL) investigated retrospectively an association between patient prognosis and the percentage of the total number of lymphoma cells found in the follicular dendritic cell (FDC) meshwork, that is, the degree of overlap of lymphoma cells. Two hundred and nine MCL patients were apportioned to grades I-III, in which the CD21-positive FDC meshwork covered ≤50%, 51%-89%, and ≥90% of the tumor area, respectively. Significant differences among the grades (all, P < 0.01) were found in the following: duration of disease (from onset of clinical manifestation to diagnosis); clinical staging; extranodal involvement (non-lymphoid organs); histological subtype; and Ki-67 proliferation index (PI). After removing the aggressive variants, the overall survival rates of grade I (n = 92) and II (n = 57) patients were similar. The overall survival rates of grade III (n = 46) patients differed from that of grade I + II patients (P < 0.01). The grades negatively correlated with the Ki-67 PI value (r = -0.234, P = 0.001). At each grade the OSR of patients with Ki-67 PI ≤30% was similar to that of patients with Ki-67 >30%. In the Ki-67 PI ≤30% group, the OSRs of the patients differed significantly among the grades. In the Ki-67 >30% group the OSRs of the grades were similar. The results of multivariate Cox regression analysis showed that the degree of overlap, age and Ki-67 PI was the independent prognostic factors of the OSRs of MCL patients. Our data suggests that MCL patients in whom there was a high degree of overlap between the FDC meshwork and tumor area have a better clinical prognosis. The degree of overlap correlates well with the Ki-67 PI, which can be used to predict the prognosis of patients.

Gastrointestinal follicular lymphoma: Current knowledge and future challenges

The gastrointestinal (GI) tract is the most commonly involved site of extranodal follicular lymphoma (FL). GI-FL shows very indolent clinical behavior and localized at GI tract without any progression or transformation compared to nodal FL. The most frequently involved site of the GI tract was the duodenum followed by the jejunum and ileum, and only 15% of FL arising in the second part of the duodenum were localized there without scattered very small daughter lesions in other GI tract examined by double-balloon endoscopy. The typical macroscopic appearance of GI-FL was multiple white nodules. Microscopically, neoplastic cells were small- to medium-sized lymphoid cells and formed neoplastic follicles. Most of the cases (>95%) were histologically Grade 1 to 2 (low grade). Several pathological and molecular characteristics were seen in GI-FL (especially duodenal FL) compared with nodal FL: immunoglobulin heavy chain deviation to VH4 and VH5; memory B-cell immunophenotype; and molecular features shared by mucosa-associated lymphoid tissue lymphoma. Considering the pathological and molecular uniqueness of this disease, GI-FL should be separately managed from nodal FL.

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.

The Expanding Spectrum of Follicular Lymphoma

Follicular lymphoma is a far more heterogeneous entity than originally appreciated. Clinical and biological variants are increasingly more granularly defined, expanding the spectrum of disease. Some variants associate with age, whereas others with anatomic site. Identification of these biologically distinct diseases has real prognostic and predictive value for patients today and likely will be more relevant in the future. Understanding of follicular lymphoma precursors has also made their identification both scientifically and clinically relevant. This review summarizes the features and understanding of follicular lymphoma, variants, and precursor lesions.

Elevation of serum interleukins 8, 4, and 1β levels in patients with gastrointestinal low-grade B-cell lymphoma

Proinflammatory cytokines that are produced by helper T cells (Th) regulate immune reactions, facilitate class switching of B cells, and prolong the lifespan of B and T cells. Eradication therapy using antibiotics is sometimes effective against gastrointestinal (GI) malignant lymphoma, suggesting that the tumor development or progression is affected by the inflammatory microenvironment. In the present study, serum samples from 148 patients with various subtypes of malignant lymphoma were tested for 11 proinflammatory Th1/Th2 cytokines. In the comparison by subtype or GI lesions, serum interleukin (IL)-8 (P = 6.7E−05), IL-4 (P = 7.5E−05), and IL-1β (P = 0.0043) levels showed significant differences among subtypes, being particularly elevated in follicular lymphomas (FL) and mucosa-associated lymphoid tissue (MALT) lymphomas. Serum IL-8 levels were elevated in GI-FL and MALT lymphomas, and serum IL-4 and IL-1 β levels were elevated in MALT lymphomas. These findings show that GI low-grade B-cell lymphoma could develop against the background of an inflammatory microenvironment. Thus, these cytokines may be useful as diagnostic markers and could provide new insights into tumor development.

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.

A multicenter survey of enteroscopy for the diagnosis of intestinal follicular lymphoma

The importance of enteroscopy examinations to investigate the entire length of the small intestines has been emphasized in follicular lymphoma patients with intestinal involvement. The aim of the present study was to determine the current state of enteroscopy examinations, including the performance rate, and the prevalence of small intestinal lesions in a patient population in Japan. A retrospective multicenter survey of 17 institutions collected the case information of 110 follicular lymphoma patients with gastrointestinal involvement. The results of the enteroscopy examinations were reviewed, and in order to identify potential factors affecting the performance rate of enteroscopy, patient gender, age at lymphoma diagnosis, histopathological grade, clinical stage, the date of the initial diagnosis and the annual volume of enteroscopy at the institution were compared between the patients who underwent one or more enteroscopy procedures and the patients who did not undergo enteroscopy. A total of 34 patients (30.9%) underwent enteroscopy, and 24 of these (70.6%) presented with involvement in the jejunum and/or ileum. It was found that more patients diagnosed in recent years and more patients treated at an ultra-high volume institution (≥101 enteroscopy examinations/year) underwent an enteroscopy. In conclusion, although the prevalence of small intestinal lesions was high (70.6%) in the follicular lymphoma patients presenting with intestinal involvement, the performance rate of enteroscopy was only 30.9%, and thus the majority of the patients have not undergone enteroscopy examinations. Further investigation is required to define the clinical significance of enteroscopy at the initial diagnostic work-up and during the follow-up period of these patients.

Primary follicular lymphoma of the duodenum

Follicular lymphoma, a common nodal lymphoma, is rare in the gastrointestinal tract. When seen in this location, duodenal involvement is frequent. Most patients have localized disease, and survival appears to be excellent even without treatment. Although the outcomes are improved, the morphologic, immunophenotypic, and genetic features remain similar to those of nodal follicular lymphomas. We describe a woman with de novo follicular lymphoma of the duodenum and discuss the features of this remarkably indolent variant of follicular lymphoma.

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.

A case report of the histologic transformation of primary follicular lymphoma of the duodenum

A 46-year-old woman underwent upper endoscopy for evaluation of anemia, which revealed whitish granules at the duodenal papilla, diagnosed as duodenal follicular lymphoma (DFL) by biopsy. Computed tomography and abdominal ultrasonography revealed that follicular lymphoma was confined to the duodenum. Seven years after the diagnosis, fluorine-18 fluorodeoxyglucose positron emission tomography scanning revealed multiple lesions including in bone marrow and lymph nodes. Bone marrow biopsy of the right iliac bone revealed diffuse large B-cell lymphoma, indicating systemic dissemination and histologic transformation of the DFL. The patient responded to chemotherapy and has been progression-free for 2.5 years. Although DFL is usually indolent even without any treatment, systemic dissemination with histologic transformation can occur. This case suggests that the life-time follow-up that is usually done for patients with nodal follicular lymphoma should be provided to patients with DFL.

A case of diffuse large B-cell lymphoma transformed from primary duodenal follicular lymphoma

Primary intestinal follicular lymphoma (FL) is a variant of FL characterized by frequent duodenal involvement and a very indolent clinical behavior without therapy. Unlike nodal FL, there have been no reports of histologic transformation (HT) or death attributable to primary intestinal FL. Here, we report the first case of primary duodenal FL showing HT. A Grade 1 FL in the duodenum was incidentally detected in a 73-year-old man. A watch-and-wait strategy was adopted because the disease was stage IE. Six months later, bone marrow involvement was suspected. The intestinal lesions had not changed during the first year since the initial diagnosis. Sixty-two months after the initial diagnosis, a biopsy specimen showed diffuse large B-cell lymphoma (DLBCL). A perforation of the intestine occurred before chemotherapy was started. Partial resection was performed and subsequent chemotherapy was administered. The clone of the initial FL and DLBCL were identical according to PCR analysis, indicating that the primary intestinal FL had transformed into DLBCL. Although HT is rare, it could occur in some patients with primary intestinal FL. Based on this case, it may be necessary to re-evaluate the clinical watch-and-wait strategy for primary intestinal FL in some patients.

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.

Five important advances in hematopathology

CONTEXT

Hematopathology is a dynamic field that has always been on the frontier of clinical research within the scope of pathology. Several recent developments in hematopathology will likely affect its practice clinically.

OBJECTIVE

To review 5 important recent advances in hematopathology: (1) detection and prognostic implication of MYC in diffuse large B-cell lymphomas, (2) determining origin and prognosis through immunoglobulin gene usage in mature B-cell neoplasms, (3)detecting minimal residual disease in multiple myeloma, (4) using genome-wide analysis in myelodysplastic syndromes, and (5) employing whole-genome sequencing in acute myeloid leukemias.

DATA SOURCES

Literature review and the authors' experiences in an academic center.

CONCLUSIONS

These advances will bring hematopathology into a new molecular era and help us to better understand the molecular, pathologic mechanisms of lymphomas, leukemias, myelomas, and myelodysplastic syndromes. They will help us to identify diagnostic and prognostic markers and eventually provide new therapeutic targets and treatments for these diseases.

Rapidly progressed primary intestinal follicular lymphoma with elevation of soluble interleukin-2 receptor levels

A 62-year-old Japanese male was diagnosed with primary intestinal follicular lymphoma involving the duodenum, jejunum, and rectum without lymph node involvement. The patient was classified as low risk by the follicular lymphoma international prognostic index (FLIPI) system. Treatment was deferred because he had no symptoms. Eleven months after the diagnosis, his soluble interleukin-2 receptor (sIL-2R) levels had risen from 383 to 617 U/mL. Lymphoma progression involving an enlarged perigastric lymph node was also documented. This report illustrates a case of rapidly progressed intestinal follicular lymphoma, suggesting the possible usefulness of sIL-2R levels as an indicator of lymphoma progression.

Elevated soluble IL-2 receptor levels correlate with tumor bulk of follicular lymphomas with intestinal involvement

OBJECTIVES

Establish a correlation between serum soluble interleukin 2 receptor (sIL-2R) levels and clinical characteristics of follicular lymphoma patients with gastrointestinal involvement.

DESIGN AND METHODS

Patients (n=44) presenting with follicular lymphoma lesions in the gastrointestinal tract were enrolled into the study and divided into 2 groups based on sIL-2R levels (normal vs. elevated). Clinical characteristics were also analyzed between groups.

RESULTS

Patients with elevated sIL-2R levels likely had systemic follicular lymphoma involvement (Ann Arbor system staging IIIES/IV or Lugano system staging II-2/IV), involvement of 5 or more nodal areas, and presentation of bulky tumors in the gastrointestinal tract. These patients also presented a high Follicular Lymphoma International Prognostic Index (FLIPI) score, suggestive of poor prognosis. No differences were found among other clinical characteristics including sex, age at lymphoma diagnosis, histological grade, LDH levels, bone marrow involvement, hemoglobin levels, and identification of tracer accumulation in gastrointestinal lesions by positron-emission tomography scanning.

CONCLUSIONS

sIL-2R levels can be used as an independent prognostic index in follicular lymphoma patients based on the correlation with the FLIPI score. Moreover, since high sIL-2R levels were associated with a large tumor bulk, sIL-2R may serve as a good indicator for monitoring disease relapse or progression.

Lymphomas of the Gastrointestinal Tract: An Update

The gastrointestinal tract is the most common extranodal site of non-Hodgkin lymphoma. Certain lymphomas have a predilection for the gastrointestinal tract, including extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, mantle cell lymphoma, natural killer/T-cell lymphoma, and enteropathy-associated T-cell lymphoma. Follicular lymphoma may also be primary to the gastrointestinal tract. In addition to diagnosing neoplastic conditions, it is important to differentiate lymphomas from atypical reactive proliferations. Recent research relevant to non-Hodgkin lymphomas involving this location is reviewed with an emphasis on novel and evolving areas of classification.

Over-expression of BACH2 is related to ongoing somatic hypermutation of the immunoglobulin heavy chain gene variable region of de novo diffuse large B-cell lymphoma

The basic region-leucine zipper (bZip) factor BTB, CNC homology 2 (BACH2) is known to have important roles in class switch recombination and somatic hypermutation (SHM) of the immunoglobulin (Ig) gene. In this study, we investigated the relationship between the expression of BACH2 and the status of SHM of the Ig heavy chain gene variable region (IgHV) for SHM in diffuse large B-cell lymphoma (DLBCL). We examined 20 cases of DLBCL, 13 of which were germinal center B-cell (GCB) DLBCL and 7 were non-GCB DLBCL. Seven cases were negative, 6 were positive (cytoplasmic expression) and 7 were strongly positive (both nuclear and cytoplasmic expression) for BACH2. Confirmed mutation (CM) was identified in 8 cases and the CM index (number of confirmed mutations per 10 subclones) was distributed from 0 to 5. A CM index of 7 strongly positive (over-expression) cases with BACH2 were distributed from 0 to 5, and that of 7 negative and 6 positive cases were distributed from 0 to 1. Over-expression of BACH2 was statistically related to CM index (P = 0.008). In conclusion, over-expression of BACH2 is critical for ongoing SHM of IgHV in DLBCL, and our data suggest that BACH2 may play an essential role for SHM of the Ig gene in B-cell lymphoma.

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.

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.

Diagnostic role of 18F-fluorodeoxyglucose positron emission tomography for follicular lymphoma with gastrointestinal involvement

AIM

To investigate the capacity for 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) to evaluate patients with gastrointestinal lesions of follicular lymphoma.

METHODS

This retrospective case series consisted of 41 patients with follicular lymphoma and gastrointestinal involvement who underwent 18F-FDG-PET and endoscopic evaluations at ten different institutions between November 1996 and October 2011. Data for endoscopic, radiological, and biological examinations performed were retrospectively reviewed from clinical records. A semi-quantitative analysis of 18F-FDG uptake was performed for each involved area by calculating the maximum standardized uptake value (SUVmax). Based on the positivity of 18F-FDG uptake in the gastrointestinal lesions analyzed, patients were subdivided into two groups. To identify potential predictive factors for 18F-FDG positivity, these two groups were compared with respect to gender, age at diagnosis of lymphoma, histopathological grade, pattern of follicular dendritic cells, mitotic rate, clinical stage, soluble interleukin-2 receptor levels detected by 18F-FDG-PET, lactate dehydrogenase (LDH) levels, hemoglobin levels, bone marrow involvement, detectability of gastrointestinal lesions by computed tomography (CT) scanning, and follicular lymphoma international prognostic index (FLIPI) risk.

RESULTS

Involvement of follicular lymphoma in the stomach, duodenum, jejunum, ileum, cecum, colon, and rectum was identified in 1, 34, 6, 3, 2, 3, and 6 patients, respectively. No patient had esophageal involvement. In total, 19/41 (46.3%) patients exhibited true-positive 18F-FDG uptake in the lesions present in their gastrointestinal tract. In contrast, false-negative 18F-FDG uptake was detected in 24 patients (58.5%), while false-positive 18F-FDG uptake was detected in 5 patients (12.2%). In the former case, 2/19 patients had both 18F-FDG-positive lesions and 18F-FDG-negative lesions in the gastrointestinal tract. In patients with 18F-FDG avidity, the SUVmax value of the involved gastrointestinal tract ranged from 2.6 to 17.4 (median: 4.7). For the 18F-FDG-negative (n = 22) and -positive (n = 19) groups, there were no differences in the male to female ratios (10/12 vs 4/15, P = 0.186), patient age (63.6 ± 2.4 years vs 60.1 ± 2.6 years, P = 0.323), presence of histopathological grade 1 vs 2 (20/2 and 17/2, P = 1.000), follicular dendritic cell pattern (duodenal/nodal: 13/5 vs 10/3, P = 1.000), mitotic rate (low/partly high, 14/1 vs 10/3, P = 0.311), clinical stage according to the Ann Arbor system (stages IE and IIE/other, 15/7 vs 15/4, P = 0.499), clinical stage according to the Lugano system (stages I and II-1/other, 14/8 vs 14/5, P = 0.489), soluble interleukin-2 receptor levels (495 ± 78 vs 402 ± 83, P = 0.884), LDH levels (188 ± 7 vs 183 ± 8, P = 0.749), hemoglobin levels (13.5 ± 0.3 vs 12.8 ± 0.4, P = 0.197), bone marrow involvement (positive/negative, 1/8 vs 1/10, P = 1.000), detectability by CT scanning (positive/negative, 1/16 vs 4/13, P = 0.335), and FLIPI risk (low risk/other, 16/6 vs 13/6, P = 0.763), respectively in each case.

CONCLUSION

These findings indicate that it is not feasible to predict 18F-FDG-avidity. Therefore, 18F-FDG-PET scans represent a complementary modality for the detection of gastrointestinal involvements in follicular lymphoma patients, and surveillance of the entire gastrointestinal tract by endoscopic examinations is required.