Primary extranodal B-cell lymphoma: current concepts and treatment strategies.

Around 30% of all non-Hodgkin lymphoma (NHL) cases arise from extranodal sites. Often the primary extranodal presentation requires site-specific strategies either for diagnosis or therapy. However, several issues remain controversial such as the definition itself of primary extranodal lymphoma, and the most appropriate staging system to characterize the disease extent. Moreover, the specific presenting sites may have per se prognostic implications. The vast majority of the published reports on primary extranodal lymphomas are represented by single-institution retrospective studies. In most clinical trials the primary extranodal lymphomas are often included together with the nodal ones and only a few studies have investigated the peculiarity of extranodal lymphomas. This review summarizes the recent advances in B-cell extranodal lymphomas, addressing the critical points in the management of the more frequently involved sites.