title: Exercise-induced pneumomediastinum.
abstract: BACKGROUND
  A sudden onset of chest pain, which often reflects a life-threatening disease, requires prompt diagnosis in the emergency department.
  
  
  RESULTS
  A 12-year-old boy presented with sustained chest pain and dyspnea after diving into a swimming pool and was transferred to our emergency department. A chest examination noted a crunching and rasping sound at the precordium, synchronous with the heartbeat. Chest radiography showed lucent streaks and the mediastinal pleura at the left cardiac outline. Additionally, computed tomography showed massive pneumomediastinum surrounding the heart. Thus, he was diagnosed with spontaneous pneumomediastinum.
  
  
  CONCLUSIONS
  Spontaneous pneumomediastinum should be considered in the differential diagnosis of chest pain. In addition to medical history-taking, careful physical examination, which can identify the characteristic finding of a friction sound synchronous with the heartbeat (Hamman's sound), will help in the immediate diagnosis of spontaneous pneumomediastinum.
authors.affiliation: Department of Cardiovascular Medicine, Saiseikai Futsukaichi Hospital, 3-13-1 Yumachi, Chikushino-shi, 818-8516, Fukuoka, Japan. tobushi@cardiol.med.kyushu-u.ac.jp.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Tobushi
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, 812-8582, Fukuoka, Japan. ncvchoso@cardiol.med.kyushu-u.ac.jp.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Hosokawa
authors.affiliation: Department of Respirology, Saiseikai Futsukaichi Hospital, 3-13-1 Yumachi, Chikushino-shi, Fukuoka, Japan. saiseikaifutsukaichi@gmail.com.
authors.forename: Keita
authors.initials: K
authors.lastname: Matsumoto
authors.affiliation: Department of Cardiovascular Medicine, Saiseikai Futsukaichi Hospital, 3-13-1 Yumachi, Chikushino-shi, 818-8516, Fukuoka, Japan. t-kadokami@saiseikai-futsukaichi.org.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kadokami
keywords: Chest pain; Emergency medicine; Spontaneous pneumomediastinum; Sports medicine