Diagnosis and management of rare gastrointestinal lymphomas.

Primary gastrointestinal (GI) lymphoma is rare, however accounts for 30-40% of cases of extranodal lymphoma. Several lymphoma subtypes have a propensity for GI tract involvement. Whilst the literature is dominated by data related to the more common extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) and diffuse large B-cell lymphoma (DLBCL) of the stomach, this review focuses on the rare subtypes of enteropathy-associated T-cell lymphoma (EATL), GI follicular lymphoma, mantle cell lymphoma (lymphomatous polyposis coli) and extranodal natural killer (NK)/T-cell lymphoma nasal-type (ENKTL). Due to its rarity, the majority of data regarding primary GI lymphoma have been derived from subgroups of larger cohorts. Clinical characteristics, prognosis and management can differ from those of nodal disease, despite corresponding histology. We discuss these differences and the challenges associated with diagnosis and management of these rare diseases.