Case Report
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Mar 6, 2020; 8(5): 963-970
Published online Mar 6, 2020. doi: 10.12998/wjcc.v8.i5.963
Muscular involvement of extranodal natural killer/T cell lymphoma misdiagnosed as polymyositis: A case report and review of literature
Li-Hui Liu, Qing Huang, Yun-Hai Liu, Jie Yang, Han Fu, Lin Jin
Li-Hui Liu, Qing Huang, Yun-Hai Liu, Jie Yang, Lin Jin, Department of Neurology, Xiangya Hospital of Central South University, Changsha 410008, Hunan Province, China
Li-Hui Liu, Qing Huang, Yun-Hai Liu, Jie Yang, Lin Jin, Department of Geriatrics Stroke Center, Cerebrovascular disease clinical research center of Hunan province, Changsha 410008, Hunan Province, China
Han Fu, Department of Dermatology, Xiangya Hospital of Central South University, Changsha 410008, Hunan Province, China
Author contributions: Huang Q dominated and guided the completion of this article; Liu LH started and finished in writing and basic ideas; Liu YH provided a lot of guidance and corrections; Yang J and Fu H provided lots of help in the process of improving the article.
Supported by the National Natural Science Foundation of China, No. 81400978.
Informed consent statement: Consent was obtained from the patient for publication of this report and the accompanying images.
Conflict-of-interest statement: The authors declare that they have no conflicts of interest.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Qing Huang, MD, PhD, Professor, Department of Neurology, Xiangya Hospital of Central South University, 87 Xiangya road, Changsha 410008, Hunan Province, China.
Received: September 26, 2019
Peer-review started: September 26, 2019
First decision: November 21, 2019
Revised: November 23, 2019
Accepted: December 13, 2019
Article in press: December 13, 2019
Published online: March 6, 2020

Natural killer (NK)/T cell lymphoma is a rare and highly aggressive malignant tumor, and is a special form of non-Hodgkin's lymphoma. Although extranodal involvement is frequently found in tissues such as the skin, testicular and gastrointestinal tract etc, its presence in skeletal muscle has scarcely been reported in the literature.


We report a case of extranodal NK/T cell lymphoma with muscle swelling as the first clinical manifestation. A 42-year-old man, who initially presented with localized swelling in the double lower extremities, demonstrated gradual facial and eyelid swelling, and his imaging results showed multiple sites of muscle damage throughout the body. The final pathological results suggested NK/T cell lymphoma, and immunohistochemistry showed CD20 (-), CD3Ɛ (+), CD30 (+), CD56 (-), EBER (+), Ki67 (60%), TIA-1 (+) and CD68 (±) staining. The muscle swelling significantly improved after treatment with chemotherapy regimens.


This disease is difficult to diagnose and highly invasive, and should be included in the differential diagnosis of unexplained muscle swelling.

Keywords: Lymphoma, Extranodal natural killer/T cell lymphoma, Muscular, Polymyositis, Muscle swelling, Case report

Core tip: Extranodal natural killer/T cell lymphoma (NK/T cell lymphoma) is a distinct clinicopathologic entity in non-Hodgkin's lymphoma, having various extranodal manifestations, and a high incidence in Asian and South American populations. In this article, we describe a 42-year-old Asian man who presented with muscle swelling as the first clinical manifestation, and was initially diagnosed with polymyositis. Upon further examination, he was definitively diagnosed with extranodal NK/T cell lymphoma. Therefore, we provide a review of the literature to further understand extranodal NK/T cell lymphoma in muscles.