Middle Eastern intestinal lymphoma.

A high incidence of intestinal lymphoma has been noted in the Middle East since the early 1960's. Initially thought to be a single entity, Middle Eastern intestinal lymphoma is now perceived as at least 3 distinct types. Mediterranean lymphoma (MTL), also known as alpha chain disease and immunoproliferative small intestinal disease (IPSID), occurs in the proximal small intestine of young adults who present with malabsorption. Histologically a phase of plasma cell infiltration is followed by invasive lymphoma. In approximately 50% of cases an alpha 1 heavy chain paraproteinaemia is present. Intestinal lymphoma of so called Western type (WTL) occurs in older patients without malabsorption or a paraproteinaemia. The lymphoma is of follicular center cell type and there is no preceding plasma cell infiltrate. Recent work suggests that both MTL and WTL belong to a distinctive group of lymphomas that specifically arise from mucosa associated lymphoid tissue. The third type of Middle Eastern intestinal lymphoma occurs predominantly in the ileo-caecal region of children and is histologically indistinguishable from Burkitts lymphoma.