title: Contributing factors in the pathogenesis of acquired cholesteatoma: size analysis based on MDCT.
abstract: OBJECTIVE
  The purpose of this article is to explore the factors that contribute to the occurrence of cholesteatoma. We studied the size of the mastoid air cells and the tympanic cavity using high-resolution CT.
  
  
  METHODS
  Temporal bone CT scans of consecutive patients with unilateral cholesteatoma and healthy control subjects were retrospectively analyzed. We compared the total volume and the greatest cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity between the affected and unaffected sides in patients with cholesteatoma and in the control subjects. We also compared separately the measured volumes of the cavities of the mastoid air cells and tympanic cavity between the unaffected side of the patients with cholesteatoma and the control subjects.
  
  
  RESULTS
  One hundred temporal bones of 50 patients with cholesteatoma and 50 control subjects were included. Both the volume and the cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity in the affected side of the patients with cholesteatoma were significantly smaller than those in the unaffected side (p < 0.001). Moreover, both the volume and the cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity in both affected and unaffected sides of patients with cholesteatoma were significantly smaller than those in control subjects (p < 0.001). The volume of the cavities of the mastoid air cells in the unaffected side of patients with cholesteatoma was smaller than that of the control subjects (p < 0.001). In contrast, no significant difference was found in the tympanic cavity volume between the unaffected side and the control subjects.
  
  
  CONCLUSIONS
  Our results were consistent with the hypothesized contribution of mastoid air cell underdevelopment to the occurrence of cholesteatoma. A small tympanic cavity is less likely to contribute to the occurrence of cholesteatoma.
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Yamashita
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshiura
authors.forename: Akio
authors.initials: A
authors.lastname: Hiwatashi
authors.forename: Dashjamts
authors.initials: D
authors.lastname: Tuvshinjargal
authors.forename: Hironori
authors.initials: H
authors.lastname: Kamano
authors.forename: Hideki
authors.initials: H
authors.lastname: Shiratsuchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018424:Cholesteatoma, Middle Ear / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology*; D015331:Cohort Studies; D004432:Ear, Middle / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008416:Mastoid / Q000000981:diagnostic imaging / Q000473:pathology*; D008875:Middle Aged; D009929:Organ Size; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult