Human herpesvirus 8-negative effusion-based lymphoma (HHV8-negative EBL) is a distinct lymphoma entity related to fluid overload states caused by underlying medical conditions. Due to a phenotypical resemblance with secondary effusion of diffuse large B-cell lymphoma (DLBCL), HHV8-negative EBL is easily misdiagnosed. However, in contrast to DLBCL, HHV8-negative EBL follows a mild clinical course, underpinning the importance to differentiate between the two entities. Only limited molecular data of HHV8-negative EBL has been reported and characteristic genomic patterns are lacking. We performed extensive genomic profiling on 8 HHV8-negative EBL cases. A mean number of 33.6 copy number gains and losses per case were found, with recurrent focal deletions of chromosome 3p14.2 and 6q21 in 6/8 cases, encompassing tumor supressor genes FHIT and PRDM1, respectively. We observed a high rate of mutations across genes frequently involved in DLBCL, including patterns of somatic hypermutation. The most abundant hotspot mutation was found in MYD88L265P (3/8 cases). In addition, 5/8 cases had one ... (Show More)

Human herpesvirus 8-negative effusion-based lymphoma (HHV8-negative EBL) is a distinct lymphoma entity related to fluid overload states caused by underlying medical conditions. Due to a phenotypical resemblance with secondary effusion of diffuse large B-cell lymphoma (DLBCL), HHV8-negative EBL is easily misdiagnosed. However, in contrast to DLBCL, HHV8-negative EBL follows a mild clinical course, underpinning the importance to differentiate between the two entities. Only limited molecular data of HHV8-negative EBL has been reported and characteristic genomic patterns are lacking. We performed extensive genomic profiling on 8 HHV8-negative EBL cases. A mean number of 33.6 copy number gains and losses per case were found, with recurrent focal deletions of chromosome 3p14.2 and 6q21 in 6/8 cases, encompassing tumor supressor genes FHIT and PRDM1, respectively. We observed a high rate of mutations across genes frequently involved in DLBCL, including patterns of somatic hypermutation. The most abundant hotspot mutation was found in MYD88L265P (3/8 cases). In addition, 5/8 cases had one or more translocations, involving MYC, BCL2, BCL6, TP63, EXOC2 and KMT2D, with Ig and non-Ig partners. We conclude that HHV8-negative EBL is characterized by genomic features that are commonly found in more aggressive B-cell lymphomas, but despite this follow an indolent clinical course.

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