Introduction: MALT (mucosal associated lymphoid tissue) lymphoma originates from the gastric mucosa in patients mainly with H.Pylori infection. Patients usually present with epigastric pain, or non-specific dyspepsia
Histopathologic changes: patients have prominent germinal centers with proliferation of lymphoid cells of marginal zone area, scattered transformed blasts with plasma cell differentiation in maximal beneath the surface epithelium and follicular colonization of the germinal center. , and prominent lymphoid epithelial lesions
Immunophenotyping: is essential in the diagnosis of MALT lymphoma (as it could mimic other higher grade lymphomas). The malignant lymphoid cells are
-CD20+, IgM+, Bcl2 +, CD5, CD10-, Cyclin D1
Chromosomal translocation t (11; 18) is the most common event in MALT lymphoma. This translocation results in the formation of MALT protein which its main action is prevention of apoptosis (cell death) and progression of cells to lymphoma
Transformation of Gastric MALT lymphoma: to large cell type is not uncommon, the percentage of large cell has to be estimated in the histopathology report either, less than 5%, 5-20% or >20%. The prognosis is worse as the percentage of large cells increases
Treatment of MALT lymphoma: 75% of all patients respond to anti-H Pylori therapy which is considered the first line of therapy in cases with MALT lymphoma.. Absence of lymph node involvement is the best predictor for response. . The complete regression takes about 5 months Repeat biopsy is recommended in theses cases in 3 months intervals for the first year, and annually for the next 5 years
In cases where no response observed (usually these are the cases with deep penetration of the lymphoid tissue, with or without regional lymph nodes involvement), other modalities should be considered; Chemotherapy with Chlorambucil or cyclophosphomide; local radiotherapy, or gastrectomy. Survival ranges in these advance cases from 75%-95% in different studies depending on the stage of the disease
Prognostic factors in the MALT lymphoma: The depth of the lymphoid infiltration in the gastric wall; the percentage of the large cells, the involvement of the regional lymph nodes and the bone marrow involvement, observed in less than 15% of the cases
Summary Diagnosing MALT lymphoma using the best knowledge with immunophenotyping in the early cases, recording all Histopathologic Prognostic Factors and not missing them for chronic gastritis in one hand, or missing them with other higher grade lymphomas (on the other hand) are the best guard for effective therapy regimens
.Dr. Hussam Abu-Farsakh, M.D