Primary testicular lymphoma.

Primary testicular lymphoma (PTL) is a rare extranodal lymphoma. The majority of cases are of diffuse large B cell lymphoma (DLBCL) histology (PT-DLBCL) with an activated B-cell-like (ABC) gene expression profile. These are characterised clinically by a high risk of contralateral testis and central nervous system (CNS) relapse, representing an ongoing area of unmet clinical need. Here, we review the epidemiology, clinical presentation and diagnostic evaluation of PT-DLBCL along with the advances in molecular biology that have occurred in the last decade, concerning the now-recognised molecular subtypes of DLBCL and their role of immune escape and sustained signalling in disease pathophysiology. We also appraise the retrospective and prospective clinical trials underpinning modern treatment recommendations, including the updated guidance on the role of radiotherapy and the latest evidence regarding strategies for preventing CNS relapse.