title: New onset of myasthenia gravis 10 years after proton beam therapy for thymoma.
abstract: A 36-year-old woman underwent proton beam therapy for encapsulated type B1 thymoma for curative intent at 66 GyE. Radiographically partial response was achieved. Although the tumor size had been stable since that time, she developed systemic myasthenia gravis 10 years after the proton therapy. Extended thymectomy was performed. There were no adhesions between the tumor and the pericardium, and there were no adhesions also between the tumor and the sternum, probably due to the favor of Bragg peak effect. Extensive hyalinization with small foci of viable tumor cells showing degenerated type A-like morphology was observed in the resected tumor. Whether the viable cells represented recurrence with degenerative changes or de novo tumor formation was unable to be determined, and whether the viable cells were responsible for the onset of myasthenia gravis remained unclear.
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Karasaki
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. murakawa-tky@umin.ac.jp.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Murakawa
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nagayama
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Nitadori
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Anraku
authors.affiliation: Department of Pathology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Kikuchi
authors.affiliation: Department of Pathology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Shinozaki-Ushiku
authors.affiliation: Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Igaki
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Nakajima
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D000069451:Long Term Adverse Effects / Q000175:diagnosis*; D009157:Myasthenia Gravis / Q000175:diagnosis*; D061766:Proton Therapy; D013945:Thymoma / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery; D014057:Tomography, X-Ray Computed
keywords: Myasthenia gravis; Radiation therapy (proton beam therapy); Thymoma