First approach on gastrointestinal lymphoma classification based on histopathology and immunohistochemistry

Background: The gastrointestinal tract is the most common site of extranodal Non-Hodgkin lymphoma, accounting for 20% to 40% of all extranodal lymphomas. This study aims to accomplish the objective: classify the prevalent histopathological patterns of gastrointestinal lymphoma according to WHO 2019 classification based on histopathology and immunohistochemistry. Subjects and methods: A cross-sectional study sampled on 76 gastrointestinal lymphoma patients to be examined and treated at The Hue University of Medicine and Pharmacy Hospital and Viet Nam National Cancer Hospital from January 2021 to June 2022. Results: B cell and T cell Lymphoma made up 97.4% and 2.6%, respectively; among them, the most common pattern was diffuse large B-cell lymphoma (59.2%,), Mucosa-associated lymphoid tissue lymphoma (17.1%), Mantle cell lymphoma (15.8%), Follicular lymphoma (2.6%), High-grade B-cell lymphoma (1.3%), and Small lymphocytic lymphoma (1.3%). The most frequent position was the stomach (60.5%), the rectum and colon, small intestine, and ileocecal region at 19.7%, 10.5%, and 9.3%, respectively. Conclusions: Using histopathology and immunohistochemistry can classify the majority of gastrointestinal Non - Hodgkin lymphoma according to the WHO 2019 classification. Immunohistochemistry plays an important role in the classification of gastrointestinal lymphomas. Key words: gastrointestinal lymphoma, WHO 2019 classification, immunohistochemistry