Definition/General
Introduction:
Primary gastric lymphoma represents 5% of gastric malignancies
MALT lymphoma is the most common type
Diffuse large B-cell lymphoma is the second most common
H
pylori infection strongly associated with MALT lymphoma.
Origin:
Arises from mucosa-associated lymphoid tissue
Acquired MALT from chronic inflammation
H
pylori-induced chronic gastritis
Autoimmune gastritis
Other infectious agents.
Classification:
WHO classification: MALT lymphoma most common
Diffuse large B-cell lymphoma
Burkitt lymphoma
T-cell lymphomas (rare)
Hodgkin lymphoma (very rare).
Epidemiology:
Peak age 50-60 years
Slight male predominance
Geographic variation
Associated with H
pylori (90% MALT)
Increasing incidence.
Clinical Features
Presentation:
Epigastric pain
Nausea and vomiting
Weight loss
Early satiety
GI bleeding
B symptoms (fever, night sweats)
Abdominal mass.
Symptoms:
Dyspepsia
Abdominal discomfort
Loss of appetite
Melena
Hematemesis
Fatigue
Constitutional symptoms.
Risk Factors:
H
pylori infection
Autoimmune disorders
Immunodeficiency
Prior radiation
Chronic gastritis
Geographic factors.
Screening:
H
pylori testing
Endoscopic evaluation
Imaging studies
Immunodeficiency screening.
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Gross Description
Appearance:
Mucosal thickening
Nodular lesions
Ulcerative lesions
Polypoid masses
Diffuse infiltration
Multiple lesions.
Characteristics:
Soft, fleshy consistency
Grayish appearance
Hemorrhage and ulceration
Wall thickening
Lymphadenopathy.
Size Location:
Antrum (MALT)
Body and fundus
Multifocal involvement
Variable size
Transmural extension.
Multifocality:
Multifocal MALT
Skip lesions
Synchronous lesions
Extragastric involvement.
Microscopic Description
Histological Features:
Monotonous lymphoid cells
MALT: Small to medium lymphocytes
DLBCL: Large lymphoid cells
Increased N/C ratio
Prominent nucleoli (DLBCL)
Mitotic activity.
Cellular Characteristics:
MALT: Centrocyte-like cells, monocytoid B-cells
DLBCL: Large cells, vesicular nuclei, prominent nucleoli
Immunoblasts
Plasma cell differentiation.
Architectural Patterns:
Diffuse infiltration
Lymphoepithelial lesions
Follicular colonization
Sheets of lymphoid cells
Background lymphocytes.
Grading Criteria:
Low-grade MALT
High-grade transformation
DLBCL grading not applicable
Ki-67 proliferation index.
Immunohistochemistry
Positive Markers:
CD20 (B-cell marker)
CD79a
BCL2
CD43 (MALT)
CD10 (variable)
BCL6 (germinal center).
Negative Markers:
CD3 (T-cell)
CD5
CD23
Cyclin D1
CD10 (MALT)
Cytokeratins.
Diagnostic Utility:
B-cell lineage confirmation
Subtype classification
Differential diagnosis
Prognostic markers.
Molecular Subtypes:
MALT lymphoma
DLBCL
Transformed MALT
ABC vs GCB subtypes (DLBCL).
Molecular/Genetic
Genetic Mutations:
t(11;18)(q21;q21) MALT
t(14;18)(q32;q21)
t(1;14)(p22;q32)
MYD88 mutations
TNFAIP3 mutations.
Molecular Markers:
API2-MALT1 fusion
BCL10 expression
NF-κB pathway
TP53 mutations (transformation).
Prognostic Significance:
Stage
H
pylori status
Chromosomal translocations
Transformation risk.
Therapeutic Targets:
H
pylori eradication
Rituximab
Chemotherapy
Radiation therapy.
Differential Diagnosis
Similar Entities:
Chronic gastritis
Reactive lymphoid hyperplasia
Adenocarcinoma
Carcinoid tumor
Metastatic lymphoma.
Distinguishing Features:
Lymphoma: Monoclonal B-cells
Gastritis: Polyclonal infiltrate
Carcinoma: Epithelial markers
Carcinoid: Neuroendocrine markers.
Diagnostic Challenges:
Low-grade MALT vs reactive
Transformed MALT
Small biopsy samples
Crush artifacts.
Rare Variants:
T-cell lymphomas
NK/T-cell lymphoma
Hodgkin lymphoma
Plasmablastic lymphoma.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
Gastric cytology, adequate for evaluation
Diagnosis
Malignant - Lymphoma, [B-cell/T-cell]
Lymphoid Features
Monomorphic [small/large] lymphoid cells
Immunophenotype
B-cell markers: [CD20+, CD79a+]
Subtype
Subtype: [MALT lymphoma/DLBCL]
Special Studies
Flow cytometry: [recommended]
Molecular studies: [recommended]
Final Diagnosis
Gastric cytology: B-cell lymphoma