title: Growth pattern changes of meningiomas: long-term analysis.
abstract: OBJECTIVE
  Although tumors are generally expected to grow exponentially, it is not known whether meningiomas retain a constant growth rate or not because of the lack of long-term follow-up. We analyzed the long-term growth pattern of meningiomas.
  
  
  METHODS
  Twenty patients with a total of 31 meningiomas were radiologically followed for 4.1 to 18.3 years (median, 10.1 yr). Seven patients (including two neurofibromatosis cases) had incidental tumors. Another 13 patients with symptomatic tumors were followed after surgery. Their volumes were measured, and their time-volume curves were plotted.
  
  
  RESULTS
  The growth curves of four atypical meningiomas fitted better to an exponential curve (R > 0.95). Two calcified tumors did not grow. Although the other benign tumors grew exponentially or linearly, their tumor volume doubling times in the initial phase were shorter than those in the later phase in most cases. Meningiomas without calcification tended to grow exponentially, whereas those with calcification were likely to reveal a linear growth pattern (P = 0.002, chi2 test). This was supported by the observation that in two patients, the tumor growth pattern changed from exponential to linear and from linear to no growth with progression of calcification.
  
  
  CONCLUSIONS
  Three growth patterns of meningiomas were demonstrated. Atypical meningiomas grew exponentially. Conversely, benign meningiomas revealed exponential, linear, or no growth. The growth pattern of the latter may change with the appearance of calcification.
authors.affiliation: Department of Neurosurgery, Shiga University of Medical Science, Ohtsu, Shiga, Japan. snakasu@belle.shiga-med.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakasu
authors.forename: Tadateru
authors.initials: T
authors.lastname: Fukami
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nakajima
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Watanabe
authors.forename: Masaharu
authors.initials: M
authors.lastname: Ichikawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsuda
mesh_terms: D000328:Adult; D000368:Aged; D002455:Cell Division / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007700:Kinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008577:Meningeal Neoplasms / Q000473:pathology*; D008579:Meningioma / Q000473:pathology*; D008875:Middle Aged; D013997:Time Factors; D014057:Tomography, X-Ray Computed