Primary extranodal lymphoma of the glands. Literature review and options for best practice in 2019

Primary extranodal non-Hodgkin's lymphomas (EN-NHL) are a heterogeneous group of malignancies that involve numerous entities with significant difference in terms of tumor site locations, prognostic factors, biology expression, and therapeutic options. In the literature, many EN-NHL types were reported from limited series which only allowed narrow views for elucidating prognostic factors and defining the role of loco-regional therapies in the era of new systemic and biologically targeted therapies. The Rare Cancer Network (RCN), an international multidisciplinary consortium, has published a number of reports on several EN-NHL sites which included many gland locations. In this review, we will focus on the recent literature for a selected number of EN-NHL types in both exocrine and endocrine gland locations. We aim to provide renewed and clear messages for the best practice in 2019 for diagnosis, histopathology, treatments, and also their prognostic implications. We believe that better understanding of molecular and genetic characteristics of these particular diseases is crucial for an appropriate management in the era of personalized treatment developments.