title: Lung adenocarcinoma with Lambert-Eaton myasthenic syndrome indicated by voltage-gated calcium channel: a case report.
abstract: BACKGROUND
  Lambert-Eaton myasthenic syndrome is a rare disorder and it is known as a paraneoplastic neurological syndrome. Small cell lung cancer often accompanies this syndrome. Lambert-Eaton myasthenic syndrome associated with lung adenocarcinoma is extremely rare; there are only a few reported cases worldwide.
  
  
  METHODS
  A 75-year-old Japanese man with a past history of chronic rheumatoid arthritis and Sjögren syndrome was diagnosed with Lambert-Eaton myasthenic syndrome by electromyography and serum anti-P/Q-type voltage-gated calcium channel antibody level preceding the diagnosis of lung cancer. A chest computed tomography to screen for malignant lesions revealed an abnormal shadow in the lung. Although a histopathological examination by bronchoscopic study could not reveal the malignancy, lung cancer was mostly suspected after the results of a chest computed tomography and [18F]-fluorodeoxyglucose positron emission tomography. An intraoperative diagnosis based on the frozen section obtained by tumor biopsy was adenocarcinoma so the patient underwent a lobectomy of the right lower lobe and lymph node dissection with video-assisted thoracoscopic surgery. The permanent pathological examination was the same as the frozen diagnosis (pT2aN1M0: Stage IIa: TNM staging 7th edition). Immunohistochemistry revealed that most of the cancer cells were positive for P/Q-type voltage-gated calcium channel.
  
  
  CONCLUSIONS
  Our case is a rare combination of Lambert-Eaton myasthenic syndrome associated with lung adenocarcinoma, rheumatoid arthritis and Sjögren syndrome, and to the best of our knowledge it is the first report that indicates the presence of voltage-gated calcium channel in lung adenocarcinoma by immunostaining.
authors.affiliation: Respiratory Disease Center, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama 232-0024, Japan. hiromasa@jg7.so-net.ne.jp.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Arai
authors.forename: Kenji
authors.initials: K
authors.lastname: Inui
authors.forename: Kazuki
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kan-O
authors.forename: Teppei
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authors.lastname: Nishii
authors.forename: Hitaru
authors.initials: H
authors.lastname: Kishida
authors.forename: Koji
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authors.lastname: Okudela
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tsuboi
authors.forename: Akinori
authors.initials: A
authors.lastname: Nozawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kaneko
authors.forename: Munetaka
authors.initials: M
authors.lastname: Masuda