title: Inverted papilloma with osteogenesis in the anterior ethmoid and frontal sinuses.
abstract: OBJECTIVE
  We report a rare case of new bone formation (osteogenesis) within an inverted papilloma, occurring in the ethmoid and frontal sinuses.
  
  
  METHODS
  The histopathological and radiological findings, differential diagnosis, and treatment of tumour-induced osteogenesis are discussed.
  
  
  RESULTS
  A 68-year-old man complained of headache and left-sided, purulent rhinorrhoea of five years' duration. On nasal endoscopy, lesions similar to inflammatory nasal polyps were seen. Pre-operative radiological images demonstrated opacification of the left nasal cavity and anterior ethmoid and frontal sinuses, plus a bone-density lesion. The mass with bony lesion was completely removed endoscopically. The mass was histopathologically diagnosed as an inverted papilloma surrounding bony tissue. Furthermore, the histopathological findings (including immature bony tissue rimmed by osteoblasts) indicated an extremely rare case of inverted papilloma induced osteogenesis. Six months after surgery, no recurrence was detected.
  
  
  CONCLUSIONS
  This case highlights the importance of clinical awareness of tumour-induced osteogenesis.
authors.affiliation: Department of Otolaryngology, Hyogo College of Medicine, Japan. kenzo@hyo-med.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Tsuzuki
authors.forename: T
authors.initials: T
authors.lastname: Nishigami
authors.forename: H
authors.initials: H
authors.lastname: Takebayashi
authors.forename: A
authors.initials: A
authors.lastname: Sakaguchi
authors.forename: H
authors.initials: H
authors.lastname: Oka
authors.forename: K
authors.initials: K
authors.lastname: Fukazawa
authors.forename: M
authors.initials: M
authors.lastname: Sakagami
mesh_terms: D000368:Aged; D004724:Endoscopy; D005005:Ethmoid Sinus; D005626:Frontal Sinus; D006801:Humans; D008297:Male; D009666:Nose / Q000000981:diagnostic imaging / Q000473:pathology; D009999:Ossification, Heterotopic / Q000473:pathology*; D018308:Papilloma, Inverted / Q000473:pathology* / Q000601:surgery; D010255:Paranasal Sinus Neoplasms / Q000473:pathology* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome