Features of Chronic Gastritis for Potential Lymphoma

Chronic gastritis and MALT lymphoma: 23 features that may prompt further workup for lymphoma in chronic gastritis include a dense lymphoid infiltrate with frequent lymphoepithelial lesions, marginal zone distribution pattern, follicular colonization, cytologic atypia, and the presence of Dutcher bodies. 2, 15, 24, 25

Morphologic evaluation: Utilizes schema such as Wotherspoon's to distinguish gastric MALT lymphoma from chronic gastritis. 15, 26

Lymphocytic gastritis: A rare form of chronic gastritis found in 1-5% of cases, associated with celiac disease and H. pylori. Defined by a minimum of 25 intraepithelial lymphocytes per 100 surface epithelial cells. 6, 27-29

Immunohistochemistry workup: CD3, CD20, and cytokeratin stains help define lymphoepithelial lesions, assess T and B cell distribution; CD5 and CD43 to look for abnormal expression; and kappa and lambda light chain assessment by ISH to evaluate for plasma cell and/or B cell restriction. 2, 30

IGH clonality or translocation studies: Indicated for gastric MALT lymphoma if clinical suspicion is present.

Chronic gastritis vs. MALT lymphoma: Chronic gastritis is most commonly caused by H. pylori infection and is characterized by a small lymphocyte and plasma cell infiltrate. MALT lymphoma has a wide variety of endoscopic findings, including a normal appearance, and may have a dense H. pylori organism presence. 1, 2, 15, 16-18

Gastric ulcer vs. gastric DLBCL: Gastric ulcers can have benign causes or be associated with tumors, including lymphoma. DLBCL commonly has associated ulcers, and careful microscopic examination is necessary to distinguish between the two. 31, 32, 33

Prolonged H. pylori infection: Believed to provide the stimulation for the development of clonal expansion leading to gastric MALT lymphoma. 2, 18, 19

Immunocompromised patients: May present with EBV-positive mucocutaneous ulcers, which have an indolent behavior. 37-39

Normal stomach: Devoid of lymphoid tissue except for scattered plasma cells and lymphocytes, and occasional mucosal lymphoid aggregates. 1, 6, 13, 14

Celiac disease: Diagnosis depends on confirmatory clinical features and serologic data. 6, 44

Stomach: H. pylori infection is the most common cause of chronic gastritis, which can lead to MALT lymphoma. Chronic gastritis is characterized by the expansion of the lamina propria by small lymphocytes and plasma cells, and the presence of H. pylori organisms around the apical side of surface cells. 1, 2, 15, 16-18.

Gastric MALT lymphoma: May have a wide variety of endoscopic findings, making it difficult to distinguish from benign gastritis. H. pylori organisms are found predominantly by the apical side of gastric surface cells. 20, 21

Ancillary studies: Special stains or targeted immunohistochemical stains may be used to aid in the evaluation process. 22

Proton pump inhibitors: May reduce the density of H. pylori organisms, making it harder to diagnose gastric MALT lymphoma. 18.

Clinical suspicion: IGH clonality or translocation studies are not recommended without clinical suspicion. 2, 15.

Malignant ulcers: More likely to be multiple and have larger size, irregular shape, uneven bases, and be present next to disrupted "moth-eaten" rugae compared to benign ulcers. 34, 35

Caution: Before making a diagnosis of DLBCL associated with ulceration, the entity of Epstein-Barr virus (EBV)-positive mucocutaneous ulcer should be considered. 37-39

Celiac disease: defined by persistent or recurrent malabsorptive symptoms and villous atrophy despite strict adherence to a gluten-free diet for 6-12 months. RCD excludes other causes and overt lymphoma.

Type 1 RCD: similar histology as celiac disease, normal immunophenotype, and polyclonal T-cell gene rearrangement studies.

Type 2 RCD: aberrant intraepithelial lymphocyte immunophenotype, clonal T-cell gene rearrangement studies, severe villous atrophy, and small lamina propria aggregates.

RCD may precede Enteropathy-associated T-cell lymphoma (EATL), a complication of celiac disease, which presents with ulcerated nodular mucosa, an occluding mass, or stricture.

EATL histologic features include lymphocyte cytologic atypia, dense lymphocytic infiltrate, angiocentricity, angioinvasion, and necrosis.

Normal small intestine: contains nodules of lymphoid tissue, including Peyer's patches, and lymphocytes in the lamina propria and intraepithelial layers.

Lymphocyte populations: duodenum contains the highest concentration of intraepithelial lymphocytes, followed by decreasing numbers towards the terminal ileum.

Lymphoid hyperplasia versus lymphoma: normal lymphoid follicles in the duodenum raise the differential of follicular lymphoma, which can be identified by loss of normal germinal center polarization and gain of BCL2 staining.

Lymphoid follicles in the colon: normal, but a small number can be found in the colonic mucosa, and focal lymphoid hyperplasia, or rectal tonsil, is common in the rectum.

Histiocytosis in the GIT: an inflammatory condition caused by a variety of mechanisms, from reactive to neoplastic, and occurs most commonly in the colon. Clinical history and immunohistochemical/special stains aid in the differential.

The text discusses the differential diagnosis of histiocytic processes in the gastrointestinal tract and aims to serve as a reference for practicing pathologists.

The luminal gastrointestinal tract contains various hematolymphoid cells, including lymphocytes, plasma cells, eosinophils, histiocytes, and mast cells.

Knowledge of normal histology and nonneoplastic processes can help distinguish benign from malignant entities.

The esophagus typically has few lymphoid cells, mostly CD8+ T cells, and rare lymphoid follicles or chronic inflammatory infiltrates.

Langerhans and mast cells are common in the esophagus, while B cells and plasma cells are not.

Involvement of the esophagus by hematolymphoid neoplasms is rare, but acquired mucosa-associated lymphoid tissue (MALT) can form.

Increased intraepithelial lymphocytes with rare granulocytes can occur in esophageal dysmotility, GERD, and esophageal candidiasis.

The esophagus is mostly devoid of lymphoid tissue.

Examination for Candida with special stains may be necessary when increased intraepithelial granulocytes or fibrinopurulent debris are present.

Lymphocytic esophagitis is a histologic diagnosis characterized by increased intraepithelial lymphocytes and associated edema and dyskeratosis.

Lymphocytic esophagitis may be associated with Crohn's disease in pediatric patients.

Features of lymphocytic esophagitis include increased intraepithelial lymphocytes, associated edema, and dyskeratosis, with few or no granulocytes.

Lymphocytic esophagitis may have a normal endoscopic appearance or show rings, furrows, or strictures.

Lymphocyte cytologic atypia, large size, lymphoid aggregates, abnormal endoscopy findings, or known other sites of disease involvement may prompt further immunohistochemical workup.

Helicobacter pylori organisms may be present in MALT lymphoma.

MALT lymphoma in the stomach may be associated with Helicobacter pylori infection.

The presence of H. pylori or organisms in the gastric mucosa does not exclude a diagnosis of MALT lymphoma.

MALT lymphoma in the stomach may be diagnosed based on histologic findings, including extranodal growth, expansion of the lymphoid follicles, and the presence of lymphoid follicles in the deeper layers of the mucosa.

Immunohistochemical markers, such as CD20, CD3, CD5, CD10, CD21, CD23, BCL2, and BCL6, can be used to confirm the diagnosis of MALT lymphoma.