How I manage patients with grey zone lymphoma.

Since grey zone lymphoma (GZL) was originally included in the 2008 World Health Organization classification as a B-cell lymphoma unclassifiable with features intermediate between diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma (cHL), new biological and clinical knowledge have been learned. It is important to highlight that diagnosis of this entity is complex and involvement by haematopathologists with expertise in this disease is recommended. It is recognized now that patients with GZL may present clinically with primary mediastinal localization or systemic disease without mediastinal involvement. Regardless of clinical presentation, patients with GZL have relatively high relapse rates, especially compared with primary mediastinal DLBCL or cHL. Interestingly, relapsed/refractory GZL patients appear to be salvaged fairly successfully, especially with haematopoietic stem cell transplantation (HSCT). Off of a clinical trial, we recommend R-CHOP (rituximab, cyclophosphamide, doxorubicin, oncovin, prednisolone) or dose-adjusted EPOCH-R (etoposide, prednisolone, oncovin, cyclophosphamide, doxorubicin, rituximab) for frontline treatment of GZL. Additionally, we advocate use of consolidative radiotherapy for localized and/or bulky disease. For patients with relapsed/refractory GZL, salvage chemotherapy followed by consolidative autologous HSCT should be considered. Finally, continued biological and pathologic examination of this unique disease entity is warranted as well as exploration towards the integration of targeted therapeutic agents (e.g., brentuximab vedotin, programmed cell death 1inhibitors, B-cell receptor inhibitors, proteasome inhibitors, etc.) into the treatment paradigm of GZL.