The recognition and classification of lymphoproliferative disorders of the gut.

Gastrointestinal lymphomas can be difficult to diagnose, particularly in small samples, when early in development, or when of unusual types. In this review, we describe lymphoid proliferations in the gastrointestinal tract in a location-based manner, including, mouth, esophagus, stomach, small intestine, and large bowel. For the purpose of differential diagnosis, benign mimics of lymphoma are also described. Lymphoma types that are specifically addressed include plasmablastic, extranodal natural killer/T-cell-nasal type, extranodal marginal zone lymphoma (eg, mucosa-associated lymphoid tissue lymphoma), diffuse large B cell, primary follicular of small intestine, enteropathy-associated T cell, and Burkitt and mantle cell. Immunohistochemical markers useful in the diagnostic approach are elaborated in detail.