Distinct genetic alterations in CD10-negative MUM1-positive follicular lymphoma

Conventional follicular lymphoma (FL) is positive for CD10 and negative for multiple myeloma oncogene 1 (MUM1). However, a subset of FL shows CD10-MUM1+ features, and the genetic alterations of this unique FL subtype are poorly understood. Thus, we conducted whole-exome sequencing in 20 cases of CD10-MUM1+ FL and analysed the genetic and clinicopathological features of these patients. The results suggested that CD10-MUM1+ FL patients were predominantly elderly women, lacked BCL2 rearrangement (17/17, 100%) ​and showed a higher grade (17/20, 85% grade 3) than patients with conventional FL. The most frequently mutated genes in these tumours were CD79B, GOLGA6L2, IGLL5, KMT2D, NFKBIE, ROBO1, BTG2, DTX1, LRP3 and PTPN6. In contrast to conventional FL, CD10-MUM1+ FL exhibited an elevated mutation frequency of CD79B and NFKBIE and decreased mutation frequencies of CREBBP, BCL2, KMT2D and TNFRSF14. No significant difference was found in the overall survival between CD10-MUM1+ FL and conventional FL patients. In summary, this study demonstrated that CD10-MUM1+ FL has unique clinical, pathological ​and genetic features.