Composite diffuse large B-cell lymphomas (DLBCLs) with peripheral T-cell lymphomas (PTCLs) are rare co-occurrences with poorly understood pathologic features. Herein, we describe 15 distinct cases of DLBCL occurring in association with PTCL, including angioimmunoblastic T-cell lymphoma (AITL; n = 12) and PTCL, not otherwise specified (n = 3). Sheets of large B cells were seen in all cases, with Hodgkin/Reed-Sternberg-like (HRS-L) cells present in 6 cases. When compared to cases of AITL without DLBCL, HRS-L cells were more frequently seen in cases of AITL with DLBCL (P = .02). Epstein-Barr virus (EBV) expression was seen in 10 of 15 cases, and in those with HRS-L cells, EBV expression was detected invariably in at least a subset of the HRS-L cells. MYC gene rearrangements were consistently absent, although 6 of the 10 cases showed MYC overexpression by immunohistochemistry in the neoplastic B cells; a frequency significantly increased compared to other cases of DLBCL not associated with a T-cell lymphoma: 29 of 166 (P = .005). In addition, when MYC was overexpressed in DLBCL, it was also weakly present in the HRS-L cells. The increased and frequent morphologic presence of HRS-L cells in association with this composite lymphoma raises a possible link between their occurrence and DLBCLs in PTCLs; furthermore, the frequent detection of MYC protein expression and EBV infection in these cases suggests a possible role of these pathways in B-cell lymphomagenesis.
Keywords: Angioimmunoblastic T-cell lymphoma; Composite lymphoma; Diffuse large B-cell lymphoma; EBV; Hodgkin/Reed-Sternberg–like cells; MYC; Peripheral T-cell lymphoma.
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