ABSTRACT
The most common lymphomas in the stomach include marginal zone lymphoma (MZL) and diffuse large B-cell lymphoma, but may also include follicular lymphoma, mantle cell lymphoma. Occasional MZL in the Gastrointestinal tract may show an extensive plasmacytic differentiation, raising the possibility of plasma cell neoplasm. Lymphoid cells have irregular nuclei and often display a characteristic monocytoid appearance with an abundant clear cytoplasm and distinct cell borders, but some tumors are composed of mostly small lymphocytes with scanty cytoplasm. The neoplastic infiltrate is often accompanied by reactive germinal centers, which are often colonized by neoplastic B cells. Infiltration and destruction of the glandular structures by clusters of neoplastic lymphocytes with formation of lymphoepithelial lesions is an important diagnostic feature of mucosa-associated lymphoid tissue (MALT) lymphoma. Intestinal MALT lymphomas are often located in the ileocecal area and the rectum. The small intestine is typically involved in patients with immunoproliferative small intestinal disease, previously called alpha-heavy chain disease.
