Primary mediastinal large B-cell lymphoma

Primary mediastinal large B-cell lymphoma (PMBCL) is a separate entity in the World Health Organization's classification, based on clinicopathologic features and a distinct molecular signature that overlaps with nodular sclerosis classic Hodgkin lymphoma (cHL). Molecular classifiers can distinguish PMBCL from diffuse large B-cell lymphoma (DLBCL) using ribonucleic acid derived from paraffinembedded tissue and are integral to future studies. However, given that similar to 5% of DLBCL can have a molecular PMBCL phenotype in the absence of mediastinal involvement, clinical information remains critical for diagnosis. Studies during the past 10 to 20 years have elucidated the biologic hallmarks of PMBCL that are reminiscent of cHL, including the importance of the JAK-STAT and NF-kappa B signaling pathways, as well as an immune evasion phenotype through multiple converging genetic aberrations. The outcome of PMBCL has improved in themodern rituximab era; however, whether there is a single standard treatment for all patients and when to integrate radiotherapy remains controversial. Regardless of the frontline therapy, refractory disease can occur in up to 10% of patients and correlates with poor outcome. With emerging data supporting the high efficacy of PD1 inhibitors in PMBCL, studies are underway that integrate theminto the up-front setting.

Automated summary

This article discusses the unique features of PMBCL and the choice of treatment options. Accurate diagnosis can be made based on clinical information and molecular classifiers, and emerging data suggest the high efficacy of PD1 inhibitors in PMBCL treatment.