Diagnosis and staging in gastrointestinal lymphoma.

The diagnosis gastrointestinal lymphoma can be made on endoscopic biopsies in the vast majority of cases. Definitive subtyping of the lymphoma according to the WHO classification with the use of additional immunological and molecular markers is the cornerstone for further decision making. Several lymphomas may occur multifocally or show both small cell and large cell components. Therefore, a second endoscopy with an extensive biopsy protocol (mapping) may be mandatory. Staging procedures are required for therapeutic decision making and should include CT-scan, laboratory studies and bone marrow examination as required in other lymphomas. Additional studies must be performed depending subtype and localisation of the lymphoma. In gastric lymphoma endosonography reveals prognostic information. In marginal zone lymphoma of MALT-type attention to other MALT-sites and autoimmune diseases is necessary. In enteropathy-associated T-cell lymphoma screening for coeliac disease and enteroscopy are required. In several lymphomas (diffuse large B-cell lymphoma and mantle cell lymphoma) a PET-scan is considered as standard of care. The value of staging procedures after treatment is less well defined. At least in gastric lymphomas, histology is the gold standard after treatment and during follow-up.