Sandbox:Mazia
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]
GI LYMPHOMA
Gastrointestinal tract is the most common extranodal site involved by lymphoma with the majority being non-Hodgkin type. Although lymphoma can involve any part of the gastrointestinal tract, the most frequent sites in order of its occurrence are the stomach followed by small intestine and ileocecal region. Gastrointestinal tract lymphoma is usually secondary to the widespread nodal diseases and primary gastrointestinal tract lymphoma is relatively rare. Gastrointestinal lymphomas are usually not clinically specific and indistinguishable from other benign and malignant conditions. Diffuse large B-cell lymphoma is the most common pathological type of gastrointestinal lymphoma in essentially all sites of the gastrointestinal tract, although recently the frequency of other forms has also increased in certain regions of the world. Although some radiological features such as bulky lymph nodes and maintenance of fat plane are more suggestive of lymphoma, they are not specific, thus mandating histopathological analysis for its definitive diagnosis. There has been a tremendous leap in the diagnosis, staging and management of gastrointestinal lymphoma in the last two decades attributed to a better insight into its etiology and molecular aspect as well as the knowledge about its critical signaling pathways.
Gastrointestinal tract is the most common extranodal site involved by lymphoma accounting for 5%-20% of all cases[1]. Primary gastrointestinal lymphoma, however, is very rare, constituting only about 1%-4% of all gastrointestinal malignancies. Gastrointestinal lymphoma is usually secondary to the widespread nodal diseases. Although virtually lymphoma can arise from any region of the gastrointestinal tract, the most commonly involved sites in term of its occurrence are the stomach followed by small intestine and ileocecal region[2]. Histopathologically, almost 90% of the primary gastrointestinal lymphomas are of B cell lineage with very few T-cell lymphomas and Hodgkin lymphoma. Certain histological subtypes have been noted to have a relative predilection site as mucosa-associated lymphoid tissue (MALT) lymphoma in stomach, mantle cell lymphoma (MCL) in terminal ileum, jejunum and colon, as well as enteropathy-associated T-cell lymphoma (EATL) in jejunum, and follicular lymphoma (FL) in duodenum with a geographic variation in its distribution[3]. Multifocality, however, has been noticed particularly in MALT lymphoma and follicular lymphoma. Certain risk factors have been implicated in the pathogenesis of gastrointestinal lymphoma including Helicobacter pylori (H. pylori) infection, human immunodeficiency virus (HIV), celiac disease, Campylobacter jejuni (C. jejuni), Epstein-Barr virus (EBV), hepatitis B virus (HBV), human T-cell lymphotropic virus-1 (HTLV-1), inflammatory bowel disease and immunosuppression[4,5]. Marker expression and translocations of common histological types of gastrointestinal lymphoma are depicted in Table Table11