Closing the gap between biology and classification in splenic B-cell lymphomas.

The mature splenic B-cell lymphomas are an enigmatic group of lymphoid neoplasms that have long caused significant difficulty for the practicing pathologist due to overlapping diagnostic features among entities and the decreasing availability of splenic tissue for assessment. While some entities have highly characteristic and specific clinicopathological features (e.g. hairy cell leukaemia), others are substantially more difficult to recognise (e.g. splenic diffuse red pulp lymphoma). At the same time, classification systems have been evolving, resulting in multiple changes to the boundaries among these entities and even the existence of some entities in their own right. Moreover, unbiased multi-omic interrogation (whole genome/transcriptome sequencing, methylome) of the splenic B-cell lymphomas over the past decade has given us significant insights into the underling biology of these neoplasms. We present a clinicopathological perspective on the historical, current and future state of the diagnosis and classification of splenic B-cell lymphomas integrating multi-omic data and highlighting areas of focus for the field in order to continue to strive to improve patient outcomes through accurate diagnosis.