Immunoproliferative Small Intestinal Disease and B-Cell MALT Lymphoma of the Digestive Tract

Immunoproliferative small intestinal disease (originally called Mediterranean lymphoma and subsequently alpha chain disease) is a slowly progressive low grade primary small intestinal B-cell lymphoma characterized by the synthesis of a truncated alpha heavy chain without light chain by the neoplastic cells. The histological features of IPSID and low grade primary gastric B-cell lymphoma are closely similar and recapitulate the those of Peyer's patches. This observation has led to the mucosa associated lymphoid tissue (MALT) lymphoma concept which encompasses a group of extranodal lymphomas including IPSID and primary gastric lymphoma. Unlike nodal low-grade B-cell lymphomas, IPSID and low grade gastric lymphoma remain localized to their sites of origin for prolonged periods. One possible explanation for this is that the growth of these lymphomas is influenced by a local antigen. This is supported by reports of clinical remissions induced in IPSID following sterilization of the small intestine using broad spectrum antibiotics. Similar findings have been reported in low grade gastric lymphoma following eradication of Helicobacter pylori which is almost invariably present in the patients' stomachs. Laboratory experiments have shown that the growth of lymphomatous B-cells is stimulated via H. pylori specific T-cells. Further work is required to identify the antigen(s) operative in IPSID and, possibly, other low grade B-cell lymphomas.