Clinicopathological features and prognosis of primary mediastinal large B-cell lymphoma: a series of sixty cases

Abstract

Objective: To investigate the clinicopathological features and prognostic factors of primary mediastinal large B-cell lymphoma (PMBL). Methods: The clinical data of 60 patients with PMBL including 44 biopsy cases and 16 consultation cases from September 2000 to November 2019 in the Department of Pathology, China-Japan Friendship Hospital (14 cases) and Peking Union Medical College Hospital (46 cases) were enrolled. Pathologic features, immunophenotype, immunoglobulin (Ig) gene rearrangement and microRNA expression profile were retrospectively studied. Results: Of the 60 patients, 23 were males and 37 were females, age ranged from 15 to 64 years (median 28 years). Immunohistochemical staining showed that the tumor cells were positive for pan-B cell antigens, CD30 (77.4%, 24/31), CD23 (73.1%, 19/26), MUM1 (45.8%, 11/24), Ki-67 index ≥70 % (90.6%, 29/32). EBER in situ hybridization was analyzed in 21 PMBL, only one case (4.8%) was positive. Ig gene rearrangement was performed in 20 cases, and seven were positive (35.0%). MicroRNA gene expression profiles were analyzed in seven cases of PMBL and nine cases of diffuse large B-cell lymphoma, and there were 33 microRNAs with significant difference (P<0.05). Univariate analysis indicated that the poor prognostic factors included serum lactate dehydrogenase (LDH) level,International Prognostic Index (IPI) score ≥3, stages Ⅲ-Ⅳ, chemotherapy not combined with rituximab and MUM1 positivity (P<0.05). Multivariate analysis showed that the treatment combined with rituximab was independently related to prognosis (P<0.05). Conclusions: PMBL is different from diffuse large B-cell lymphoma in clinicopathologic features, immunophenotypic presentation and molecular features. The prognostic factors, molecular genetics and immunological characteristics reveal that this study has enriched our understanding of the biology of PMBL, thus providing evidence and strategies for treatment.