Pathology of intestinal lymphomas.

The advent of immunohistological and molecular techniques has enabled the comprehensive characterization of many lymphoma entities. Furthermore, it has increased the consensus in lymphoma classification among pathologists. In this review we describe the pathological features of primary intestinal lymphomas classified according to the revised European-American classification of lymphoid neoplasms. The majority of primary intestinal lymphomas are of B-cell lineage and most of these are high-grade tumors. By morphology they may be classified as diffuse large B-cell lymphomas of centroblastic, immunoblastic or plasmablastic type and Burkitt lymphomas. The latter occur predominantly in the terminal ileum and affect children or young adults. Low-grade extra-nodal marginal-zone lymphoma of the mucosa-associated lymphoid tissue (MALT) type and, less frequently, follicular center-cell lymphomas are the low-grade B-cell lymphomas most commonly observed in this region. The first mentioned tumor and its specific intestinal variant, alpha-chain disease or immunoproliferative small intestinal disease are well known for their indolent clinical course. Primary intestinal mantle-cell lymphoma often presents as multiple lymphomatous polyposis and similarly to its node-based equivalent is associated with an unfavorable prognosis. Most primary intestinal T-cell lymphomas display a characteristic immunophenotype, particular histological features with prominent epitheliotropism and are often associated with celiac disease indicating that these tumors form a specific lymphoma type. It has been termed intestinal T-cell lymphoma or enteropathy-type T-cell lymphoma. Clinically, these are aggressive diseases with a high mortality rate. In summary, primary intestinal lymphomas consist of several entities which display distinct clinicopathological features thus confirming the relevance of lymphoma typing.