Clinicopathological differences in MYC and BCL2 protein expression between primary extranodal and nodal diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) exhibits clinical, genetic, and immunohistochemical heterogeneity. However, the differences between primary extranodal or nodal DLBCL and double-expressor lymphoma (DEL), which is characterized by high MYC and BCL2 expression, remain unclear. This study aimed to elucidate the clinicopathological features, response to therapy, and clinical outcomes of primary extranodal (n=61) and nodal (n=128) DLBCL. Patients with primary nodal DLBCL had higher BCL2 expression than those with extranodal DLBCL (p=0.048), with high MYC expression and DEL as poor prognostic factors. Conversely, in patients with primary extranodal DLBCL, high BCL2 expression, low BCL6 expression, non-germinal center B-cell-like type, and DEL indicated poor prognosis. DEL was significantly associated with progression free survival and overall survival in patients with primary extranodal DLBCL (p=0.014 and p=0.021, respectively) but not in patients with primary nodal DLBCL (p=0.37 and p=0.084, respectively). Our findings highlight primary extranodal DEL as a strong adverse prognostic factor in DLBCL.