Open Peer Review Any reports and responses or comments on the article can be found at the end of the article. CASE REPORT Case Report: Malignant Thymoma And Seronegative Myasthenia Gravis [version 1; peer review: 1 approved with reservations] Cláudia Sousa , Mafalda Cruz, Ana Neto, Kayla Pereira, Mónica Henriques, Rui Marques, Paula Alves Radiotherapy Department, Portuguese Institute of Oncology of Coimbra, Coimbra, Portugal Abstract Myasthenia gravis (MG) is present in 50% of thymomas and is rarely associated with thymic carcinoma. We present the case of a 49-year-old woman with malignant thymoma, treated with surgery followed by radiotherapy, and a late seronegative MG diagnosis. This case reports the importance of a multidisciplinary approach to the management of the potential correlation of malignant and benign diseases. Keywords Seronegative myasthenia gravis, malignant thymoma, tomotherapy, paraneoplastic disorder. Cláudia Sousa ( ) Corresponding author: claudiacarreirosousa@gmail.com : Conceptualization, Methodology, Resources, Writing – Original Draft Preparation, Writing – Review & Editing; : Author roles: Sousa C Cruz M Methodology, Validation, Writing – Review & Editing; : Methodology, Validation, Writing – Review & Editing; : Validation, Writing – Neto A Pereira K Review & Editing; : Validation, Writing – Review & Editing; : Supervision, Validation, Writing – Review & Editing; : Henriques M Marques R Alves P Validation, Writing – Review & Editing No competing interests were disclosed. Competing interests: The author(s) declared that no grants were involved in supporting this work. Grant information: © 2019 Sousa C . This is an open access article distributed under the terms of the , which Copyright: et al Creative Commons Attribution License permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Sousa C, Cruz M, Neto A How to cite this article: et al. Case Report: Malignant Thymoma And Seronegative Myasthenia Gravis [version F1000Research 2019, :2110 ( ) 1; peer review: 1 approved with reservations] 8 https://doi.org/10.12688/f1000research.21393.1 16 Dec 2019, :2110 ( ) First published: 8 https://doi.org/10.12688/f1000research.21393.1 Reviewer Status Invited Reviewers version 1 published 16 Dec 2019 1 report , Fondazione Policlinico Bruno Fionda Universitario “A. Gemelli” IRCCS, Rome, Italy 1 16 Dec 2019, :2110 ( First published: 8 ) https://doi.org/10.12688/f1000research.21393.1 16 Dec 2019, :2110 ( Latest published: 8 ) https://doi.org/10.12688/f1000research.21393.1 v1 Page 1 of 6 F1000Research 2019, 8:2110 Last updated: 27 DEC 2019