[Pathology of intestinal lymphomas].

Intestinal lymphomas are almost exclusively non-Hodgkin lymphomas (NHL) which occur at a slightly lower frequency than those arising in the stomach. Intestinal NHLs differ from nodal lymphomas because they retain some properties of the mucosa-associated lymphoid tissue (MALT) from which they arise. The recently proposed WHO classification of lymphoid neoplasias encompasses and defines all the NHLs occurring in the gastrointestinal tract as lymphoma entities. The histopathological diagnosis relies on the combination of morphology and immunohistochemistry, which represents the gold standard. By this means a correct diagnosis can be achieved in the vast majority of cases. If nevertheless diagnostic problems arise, they can usually be managed by a re-biopsy, or in individual cases by molecular studies. At any rate, the pathologist must classify the lymphoma according to the WHO classification and diagnoses such as "low-grade B-cell lymphoma" or "small B-cell lymphoma" are not acceptable.