Case Report/Case SeriesIsolated Primary Neurolymphomatosis in the Right Brachial Plexus Proven by Partial Nerve BiopsyLee, Gin Hoong MD*; Hsueh, Hsueh-Wen MD, MS*; Wang, Kuo-Chuan MD, PhD†; Yu, Shan-Chi MD, PhD‡; Huang, Hsin-Yi MD, PhD‡; Chao, Chi-Chao MD, PhD*; Hsieh, Sung-Tsang MD, PhD* Author Information *Department of Neurology †Department of Surgery ‡Department of Pathology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan Informed consent was obtained from the participant included in the study with their personal or clinical details and any accompanying images. The authors confirm that they have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines. All authors contributed to data acquisition and analysis. G.H.L., H.W.H., and S.T.H. wrote the manuscripts with input from all authors. All procedures performed in studies involving human participants were in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The authors declare no conflicts of interest. Correspondence to: Hsueh-Wen Hsueh, MD, MS, Department of Neurology, National Taiwan University Hospital, No. 7 Chung-Shan South Road, Taipei, 10002, Taiwan. E-mail: [email protected]. Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's website, www.theneurologist.org. The Neurologist: November 15, 2022 - Volume - Issue - 10.1097/NRL.0000000000000471 doi: 10.1097/NRL.0000000000000471 Buy SDC PAP Metrics Abstract Introduction: Isolated primary neurolymphomatosis is a rare manifestation of lymphoma, which is challenging to diagnose as there is only involvement of the nervous system, and nerve biopsy is not frequently pursued due to the high risk of irreversible complications. Case Report: We present a case of isolated primary neurolymphomatosis of diffuse large B-cell lymphoma restricted to only the right brachial plexus and right axillary nerve. The clinical course has been indolent for several years. The initial examination, including MRI and the cerebrospinal fluid study, did not yield any evidence of malignancy. Eventually, due to the patient’s symptom progression and the follow-up imaging findings, we conducted a partial nerve biopsy of the brachial plexus to confirm the malignancy. His neurological symptoms did not further deteriorate post-biopsy. Conclusion: Isolated primary neurolymphomatosis with an indolent course is rare and challenging to diagnose. Serial MRI and fluorodeoxyglucose-positron emission tomography reveal clues for tumor involvement. Partial nerve biopsy or targeted fascicular nerve biopsy could be an alternative for achieving a pathologic diagnosis. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.