Primary gastric lymphomas: morphologic, immunohistochemical and immunogenetic analyses

Estimating the prevalence of Epstein-Barr virus in primary gastric lymphoma: a systematic review and meta-analysis

The stomach is a common site for extranodal non-Hodgkin's lymphoma. While Helicobacter pylori (H. pylori) is the main established risk factor for primary gastric lymphoma, a fraction could be aetiologically associated with Epstein-Barr virus (EBV), a known haematolymphoid carcinogen. We systematically searched five databases from 1 January 1990 until 31 May 2022 for studies reporting EBV prevalence in gastric lymphoma tumour tissue by in-situ hybridisation (ISH) for EBV-encoded small RNA (PROSPERO CRD42020164473). We included representative series of more than five gastric lymphoma cases. Pooled prevalence and corresponding 95% confidence intervals (CI) of EBV in gastric tumour cells were calculated for two major gastric B-cell lymphoma types, mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma (DLBCL). When available, we also extracted data on H. pylori prevalence and survival by EBV status. We found ten studies including 194 cases of gastric MALT lymphoma and 11 studies including 643 cases of gastric DLBCL. EBV prevalence was 2.2% (95% CI: 0.5-13.3) in gastric MALT lymphoma and 11.0% (95% CI: 5.2-20.0) in gastric DLBCL. In a subset of studies, the prevalence of H. pylori was higher in gastric MALT lymphoma (51/69) compared to gastric DLBCL (62/102). Overall, our findings suggest that EBV is rarely seen in MALT lymphoma but is associated with around 10% of gastric DLBCL, similar to the proportion observed at other primary sites. EBV-related lymphoma adds a small number of cases to the burden of cancer that could be prevented by the future development of a vaccine against EBV.

Usefulness of magnifying endoscopy and endoscopic ultrasonography for the gastric involvement of follicular lymphoma

A 61-year-old man received an esophagogastroduodenoscopy for further investigation of mesenteric lymphadenopathy. Esophagogastroduodenoscopy revealed swollen gastric folds and cobble stone mucosa in the gastric body. Magnifying endoscopy with narrow-band imaging showed branched abnormal vessels and the absence or destruction of gastric pits. Endoscopic ultrasonography (EUS) depicted homogeneously hypoechoic thickening of the submucosal layer where the mucosal changes were observed. The patient was diagnosed with follicular lymphoma by biopsy of these lesions. We should recognize that these endoscopic features are consistent with follicular lymphoma involving the stomach and that concurrent EUS is useful for diagnosis and identification of adequate biopsy sites.

Consolidation Radiotherapy in Stage IE- IIE, Non-Bulky Primary Gastric Diffuse Large B-Cell Lymphoma with Post-Chemotherapy Complete Remission

Background

To investigate the effects of consolidation radiation in patients with stage IE-IIE, non-bulky primary gastric diffuse large B-cell lymphoma (DLBCL).

Methods

A cohort consisted of 71 consecutive patients with stage IE-IIE, non-bulky primary gastric DLBCL was retrospectively analyzed. All of them had been in complete remission after receiving at least four cycles of chemotherapy, containing rituximab or not. Consolidation radiation was delivered thereafter in 28 patients while other 43 received clinical observation only. Locoregional relapse-free survival (LRFS), disease-free survival (DFS), overall survival (OS) and distant metastasis-free survival (DMFS) were compared between patients with or without radiotherapy.

Results

The 10-year LRFS, DFS, OS and DMFS were 100% and 81.4% (p = 0.028), 91.7% and 77.1% (p = 0.14), 91.7% and 77.8% (p = 0.67), 91.7% and 78.0% (p = 0.42) for patients with or without radiotherapy.

Conclusions

Radiotherapy is associated with improved locoregional control of patients with early stage primary gastric DLBCL, who have achieved complete remission following at least four cycles of chemotherapy.

Primary diffuse large B-cell lymphoma of the stomach

The stomach is the extranodal site most commonly involved by non-Hodgkin lymphomas. Diffuse large B-cell lymphoma is the most common histotype category arising in this organ. This is an aggressive lymphoma usually presenting as limited disease, being associated or not to Helicobacter pylori infection and mucosa-associated lymphoid tissue-type areas. Histopathological characteristics are similar to those reported for other diffuse large B-cell lymphomas. It occurs more frequently in males with a median age ranging between 50 and 60 years. With an adequate therapeutic strategy, its prognosis is good, with a 5-year overall survival near to 90%. Conservative treatment with anthracycline-containing chemotherapy, followed or not by involved-field radiotherapy has replaced gastrectomy as standard approach against this malignancy. Several questions on the best treatment remain unanswered. Among others, the role of rituximab, consolidation radiotherapy as well as of more conservative approaches like H. pylori-eradicating antibiotic therapy should be better defined.

Primary gastrointestinal tract lymphoma: diagnosis and management of common neoplasms

Primary gastrointestinal lymphoma represents the most common location of extranodal lymphoma. With the bulk of disease manifesting within the gastrointestinal tract and contiguous lymph nodes, many of the lymphomas occurring in the peripheral lymph nodes can also present with primary gastrointestinal tract involvement. Molecular biology has recently enabled significant progress in the diagnosis and management of primary gastrointestinal lymphoma. Herein, we will discuss the major lymphomas affecting the bowel and highlight their key morphological, immunophenotypical and molecular diagnostic attributes. Similarly, in keeping with recent therapeutic advances, we will briefly discuss some important treatment considerations. Thus, this review is intended to offer clinicians and pathologists an overview of primary gastrointestinal lymphomas.

Clinicopathologic and immunohistochemical study of surgically treated primary gastric MALT lymphoma

BACKGROUND AND OBJECTIVES

B-cell MALT lymphoma is a well-recognized entity and its characterization as low-grade (LG) and high-grade (HG) lymphoma has been widely accepted. In the present study we reviewed a series of 95 surgical specimens of primary gastric MALT lymphoma selected between 1979 and 1998. Immunohistochemical expression of p53, bcl-2, and Ki67 and Helicobacter pylori (Hp) infection was evaluated, along with a correlation with clinical outcome.

METHODS

A morphologic and immunohistochemical analysis, including p53, bcl-2, and Ki67 expression, was carried out in all cases. A complete follow-up was obtained in 49 patients and in these cases a survival analysis was performed.

RESULTS

bcl-2 protein was highly expressed in 25 of 25 assessed LG tumors and in 20 of 24 assessed HG tumors. p53 protein was expressed in 13 of 25 assessed LG tumors and in 21 of 24 assessed HG tumors. High proliferation rate as expressed by Ki67 was detected in 15 of 25 assessed LG tumors and in 23 of 24 assessed HG tumors. Hp infection was detected in 11 of 16 assessed LG tumors and 2 of 10 assessed HG tumors. Median survival rates were 72 months for LG tumors and 24 months for HG tumors.

CONCLUSIONS

A significant inverse relationship between Hp infection and histological grade was found. High p53 expression and high-proliferation rate correlated with HG tumors. However, a correlation between p53, bcl-2, and Ki67 expression with clinical outcome was not found.

Histopathologic features and expression of Bcl-2 and p53 proteins in primary gastric lymphomas

The aim of this study is to present a histopathologic and immunohistochemical analysis of primary gastric lymphomas which were reclassified according to the concept of mucosa associated lymphoid tissue (MALT). The resected specimens from 41 patients with primary gastric lymphoma were investigated retrospectively. Immunohistochemical study was done to analyze the immunophenotype and bcl-2 and p53 proteins expression. Twenty three of the cases had tumors mainly located in the antrum. Histologically, 12 were low grade and 20 were high grade B-cell lymphoma of MALT, 9 other B-cell nonHodgkin's lymphomas. Helicobacter pylori was identified in 72% of the cases. According to Musshoff's modification, most of the MALT lymphoma cases had stage I or II disease. There was significant difference between low and high grade cases, in respect to depth of invasion in gastric wall. Immunohistochemically, the neoplastic cells in all MALT lymphomas expressed B-cell phenotype. Bcl-2 protein was found to be expressed in 59% and p53 protein expression was detected in 72% of cases. Among the B-cell lymphoma of MALT, bcl-2 positivity decreased and p53 positivity increased significantly as the histological grade advanced. So, an inverse correlation was observed between the expression of bcl-2 and p53. In conclusion, most primary gastric lymphomas are low or high grade B-cell MALT lymphomas and appear to arise in MALT acquired as a reaction to Helicobacter pylori infection. Expression of bcl-2 and p53 in gastric lymphomas may be associated with transformation from low-grade to high-grade disease.

Origin of primary gastric T-cell lymphomas from intraepithelial T-lymphocytes: report of two cases

AIMS

The classification of primary gastric T-cell lymphomas is uncertain due to the exceeding rarity of these tumours; many of the reported cases were felt to be similar to node-based lymphomas. We describe two cases of primary gastric T-cell lymphoma with evidence of origination from intraepithelial T-lymphocytes.

METHODS AND RESULTS

Both tumours were restricted to the stomach; one displaying a large ulcerated mass, the other a widespread superficial tumour manifestation. Histologically the first tumour was composed of sheets of medium-sized lymphoid cells showing marked epitheliotropism at the edge of the ulcer, and a CD3+, CD4-, CD8-, CD20-, CD56-, CD103+, beta F1+ phenotype. The second case differed histologically and immunophenotypically from the first case. In addition to lamina propria and submucosal infiltration, the lymphoma contained an extensive intraepithelial component even in large areas without other evidence of tumour. The neoplastic cells ranged in size from small to medium and large. Immunohistology disclosed a CD3+, CD4+, CD8-, CD20-, CD56-, beta F1+ phenotype. Staining for CD103 could not be performed in this case since frozen material was not available.

CONCLUSIONS

The prominent epitheliotropism, the marked intraepithelial growth and the expression of CD103 strongly imply a derivation of these primary gastric lymphomas from intraepithelial T-lymphocytes. Additional studies of larger series will clarify whether the findings described here are typical of primary gastric T-cell lymphomas.

Gastric low-grade mucosa-associated lymphoid tissue lymphomas: their histogenesis and high-grade transformation

Gastric low-grade mucosa-associated lymphoid tissue (MALT) lymphoma is a unique disease. A vast majority of lymphoma cells are centrocyte-like cells or resemble monocytoid B cells, and occasionally show plasmacytic differentiation. Immunophenotypical and immunogenotypical examinations have indicated that they are in the differentiation stage of memory B cells, whose normal counterparts are marginal zone lymphocytes or monocytoid B cells in the lymphoid tissues. It arises from chronic gastritis closely associated with Helicobacter pylori (H. pylori) infection. Mucosa-associated lymphoid tissue lymphomas of other organs are also based on acquired MALT associated with chronic inflammation or autoimmune diseases. Interestingly, the majority of gastric low-grade MALT lymphomas regress by the eradication of H. pylori. The lymphoma cells, however, are not derived from B cells reacting with H. pylori itself but from autoreactive B cells. Although the mechanism of their oncogenesis has not been clarified, previous data suggest that autoreactive B cells proliferate in response to H. pylori-specific T cells, presumably with some cytokines. The genetic instability of such B cells then induces chromosomal abnormalities including trisomy 3 and/or other genetic changes. These B cells have the ability of autonomic proliferation and, even so, they might be sensitive to T cell stimuli. Low-grade gastric lymphomas occasionally progress to high-grade malignancy. The high-grade component of MALT lymphomas are composed of large-sized lymphoma cells that are morphologically indistinguishable from nodal large B cell lymphomas. This high-grade transformation is associated with p53 abnormalities or Bcl-6 overexpression. Gastric MALT lymphoma may provide a useful model in understanding multistep lymphomagenesis.