Helicobacter pylori infection and MALT lymphoma

Abstract

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT), also known as MALT lymphoma, is an indolent B-cell non-Hodgkin lymphoma, arising in lymphoid infiltrates that are induced by chronic inflammation in extranodal sites. The stomach is the most commonly affected organ, where MALT lymphomagenesis is clearly associated with Helicobacter pylori gastroduodenitis. Outside the stomach, the role of infectious agents is less clearly defined. In recent years, gastric MALT lymphoma became the focus of attention because of the involvement of its genetic aberrations in the nuclear factor kappa B (NF-ĸB) pathway, currently one of the most investigated pathways in the fields of immunology and oncology. This chapter presents gastric MALT lymphoma as an outstanding example of the close pathogenic link between Helicobacter pylori-induced chronic inflammation and tumour development. It also presents gastric MALT lymphoma as one of the best models of how genetic events initiate oncogenesis, determine tumour biology, dictate clinical behaviour and represent viable therapeutic targets. Moreover, in view of the association of gastric MALT lymphoma with deregulation of the NF-° B pathway, the latter signalling pathway is also discussed in depth in both physiological and pathological conditions.