Contemporary approach to the diagnosis and classification of intestinal T-cell lymphomas.

We provide an overview of recent advances in the diagnosis and classification of intestinal T- and NK-cell lymphomas and lymphoproliferative disorders that primarily involve the gastrointestinal (GI) tract. It should be mentioned that systemic T- and NK-cell lymphomas can present initially in the GI tract but are not the focus of this review. Here, we focus on the clinical and pathologic findings of enteropathy-associated T-cell lymphoma, monomorphic epitheliotropic intestinal T-cell lymphoma, intestinal T-cell lymphoma, not otherwise specified, indolent T-cell lymphoma of the GI tract and indolent NK-cell lymphoproliferative disorder of the GI tract (previously known as NK-cell enteropathy). These diseases are uncommon, and their clinical manifestations and pathologic features can show overlap, but are associated with different outcomes making accurate diagnosis essential. In most cases, the diagnosis of intestinal T- and NK-cell lymphomas and lymphoproliferative disorders requires integrating the clinical context with the morphologic, immunophenotypic, and molecular alterations. In this review, we also emphasize the current understanding of the genetic drivers of these diseases.