Primary gastrointestinal T-cell lymphomas: concepts and diagnostic insights

The gastrointestinal tract represents the most common site of extranodal non-Hodgkin lymphoma. Malignant lymphomas represent up to 4% of all malignant neoplasms of the GI tract. Overall, lymphomas of B-cell lineage predominate. T-cell lymphomas are uncommon and account for 6% of all GI tract lymphomas. Intestinal T-cell lymphomas comprise a heterogeneous group of lymphoproliferative neoplasms with distinct morphologic, immunophenotypic, and genetic features. Based on the recently revised 2017 WHO classification, intestinal T-cell lymphomas are categorized into four distinct entities: Enteropathy-associated T-cell lymphoma (EATL), monomorphic epitheliotropic intestinal T-cell lymphoma (METL), intestinal T-cell lymphoma, not otherwise specified (ITCL, NOS) and indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. Herein, we aim to create awareness of these uncommon neoplasms with emphasis on key diagnostic points.