ABSTRACT
This chapter provides an overview of the main challenging questions and controversial issues that one has to tackle when dealing with the management of extranodal lymphomas. The term extranodal lymphoma encompasses a vast assortment of morphologies, molecular alterations, and clinical presentations. The exact designation of extranodal lymphoma is controversial, particularly in the presence of both nodal and extranodal disease. The proportion of non-Hodgkin’s lymphomas presenting at extranodal sites accounts for from one-quarter to more than one-half of new lymphoma cases, with important geographic variations. The influence of the localization site on the outcome is less clear in mucosa-associated lymphoid tissue lymphoma, where multifocal lesions are present in 20–40% of patients. Dissemination is more frequent in non-gastric lymphomas and can occur either to other mucosal sites or to a non-mucosal site such as spleen, bone marrow, or liver. Considering the many variables which influence site-specific outcome in extranodal lymphomas, it is questionable whether a general distinction has clinical relevance.
