[Nodal T-follicular helper cell lymphoma, angioimmunoblastic-type associated with diffuse large B-cell lymphoma: a clinicopathological study].

Objective: To investigate the clinicopathological features and molecular genetics of diffuse large B-cell lymphomas (DLBCL) with concurrent or secondary to nodal T-follicular helper cell lymphoma, angioimmunoblastic-type (nTFHL-AI). Methods: The clinicopathological features and molecular genetics of DLBCL associated with nTFHL-AI diagnosed between January 2015 and October 2022 at the First Affiliated Hospital of Zhengzhou University were analyzed using histology, immunohistochemistry, PCR, EBV-encoded RNA in situ hybridization and fluorescence in situ hybridization (FISH). Clinical information was collected and analyzed. Results: A total of 6 cases including 3 nTFHL-AI with secondary DLBCL and 3 composite lymphomas were reviewed. There were 4 male and 2 female patients, whose ages ranged from 40 to 74 years (median 57 years). All patients presented with nodal lesions at an advanced Ann Arbor stage Ⅲ/Ⅳ (6/6). Bone marrow involvement was detected in 4 patients. All cases showed typical histologic and immunophenotypic characteristics of nTFHL-AI. Among them, 5 cases of DLBCL with concurrent nTFHL-AI exhibited numerous large atypical lymphoid cells and the tumor cells were CD20 and CD79α positive. The only case of DLBCL secondary to nTFHL-AI showed plasma cell differentiation and reduced expression of CD20. All of cases were activated B-cell (ABC)/non-germinal center B-cell (non-GCB) subtype. Three of the 6 cases were EBV positive with>100 positive cells/high power field, meeting the diagnostic criteria of EBV⁺DLBCL. The expression of MYC and CD30 protein in the DLBCL region was higher than that in the nTFHL-AI region (n=5). C-MYC, bcl-6 and bcl-2 translocations were not detected in the 4 cases that were subject to FISH. Four of the 6 patients received chemotherapy after diagnosis. For the DLBCL cases of nTFHL-AI with secondary DLBCL, the interval was between 2-20 months. During the follow-up period ranging from 3-29 months, 3 of the 6 patients died of the disease. Conclusions: DLBCL associated with nTFHL-AI is very rare. The expansion of EBV-infected B cells in nTFHL-AI may progress to secondary EBV⁺DLBCL. However, EBV-negative cases have also been reported, suggesting possible other mechanisms. The up-regulation of MYC expression in these cases suggests a possible role in B-cell lymphomagenesis. Clinicians should be aware that another biopsy is still necessary to rule out concurrent or secondary DLBCL when nodal and extranodal lesions are noted after nTFHL-AI treatment.