Original ArticlesMorphologic Patterns and the Correlation With MYD88 L265P, CD79B Mutations in Primary Adrenal Diffuse Large B-Cell LymphomaChen, Zihang MD; Zou, Yan MM; Liu, Weiping MD; Guan, Pujun MM; Tao, Qing MD; Xiang, Chunxiang PhD; Zhang, Wenyan MD, PhD; Ye, Yunxia MD; Yan, Jiaqi PhD; Zhao, Sha MD, PhDAuthor Information Department of Pathology, West China Hospital, Sichuan University, Chengdu, China Conflicts of Interest and Source of Funding: Supported by the National Natural Science Foundation of China (30900534) and Sichuan Science and Technology Program (2018JY0612). The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Sha Zhao, MD, PhD, Department of Pathology, West China Hospital, Sichuan University, No. 37, GuoXue Xiang, Chengdu, Sichuan 610041, China (e-mail: [email protected]). The American Journal of Surgical Pathology: April 2020 - Volume 44 - Issue 4 - p 444-455 doi: 10.1097/PAS.0000000000001386 Buy SDC Metrics Abstract Primary adrenal diffuse large B-cell lymphoma (PA-DLBCL) is a rare subtype of extranodal DLBCL. Because of the rarity of this disease, its morphologic and genetic features are not comprehensively studied. Here, we systematically reviewed the clinicopathologic features of 42 cases of PA-DLBCL from our institution and investigated the frequency of MYD88 L265P and CD79B (exon 5) mutation in 29 eligible cases using Sanger sequencing. Clinically, PA-DLBCL was predominant in elderly male patients with advanced clinical stage and poor outcomes. Morphologically, the tumors often showed a sinusoidal and/or cohesive pattern with condensed chromatin and inconspicuous nucleolus which mimicked neuroendocrine carcinoma. Moreover, increased Reed-Sternberg–like cells were observed frequently. These confounding morphologic manifestations may lead to misdiagnosis. Genetically, PA-DLBCL harbored a high prevalence of MYD88 L265P (24%) and CD79B mutations (52%) which may be involved in lymphomagenesis. The CD79B mutation was significantly associated with a worse prognosis. A novel Histo-Molecular Classification system (4 categories) was proposed based on correlation with genetic changes. Generally, the neuroendocrine carcinoma–like type was associated with CD79B mutation, whereas the RS-like cell type indicated MYD88 L265P. The biphasic type was correlated with coexisting mutations of MYD88 and CD79B, whereas the common type implied no mutation. Furthermore, the common type showed significantly better survival. In conclusion, the proposed new category system could indicate the genetic changes as well as facilitate risk stratification to guide treatment and predict prognosis. Although this study augmented our understanding of PA-DLBCL, further analysis is required to validate our results and extend them to extranodal DLBCL at other sites. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.