433 Single-cell characterization of primary cutaneous B-cell lymphomas reveals distinct clonal properties of marginal zone, follicle center and leg-type lymphomas

Primary cutaneous B-cell lymphomas (CBCL) comprise a group of extranodal non-Hodgkin that are primarily confined to the skin. marginal zone lymphoma (MZL) and follicle center (FCL) associated with rather indolent tumor behavior, while diffuse large lymphoma, leg type (DLBCL-LT) shows an aggressive clinical course. Besides distinct immune-histological features, underlying molecular biology is still only insufficiently understood. Therefore, we performed single-cell RNA sequencing combined receptor in different CBCL entities pseudolymphoma. We observed expansion single clone only. So-called pseudolymphoma was identified be polyclonal as expected. Expanded clones MZL showed terminal differentiation along physiological trajectory from unswitched towards switched immunoglobulin phenotypes included numbers plasma cells. Overall transcriptomic profiles were indistinguishable benign B cells, line its FCL also exhibited canonical marker profile, but proliferating non-proliferating germinal By contrast, DLBCL-LT cells uniquely multiple aberrant including proliferative activity beyond conventional center-like phenotypes, pursuant behavior. Moreover, TME comprising T- B-cells decreased number diversity over confirmed through multiplex situ IF. Our data revealed show transcriptionally expanded clone, differentiate trajectories, suggestive lymphoproliferative disorder than overt lymphoma.