title: How do spinal schwannomas progress? The natural progression of spinal schwannomas on MRI.
abstract: OBJECTIVE
  Little is known about the progression of spinal schwannomas. The aim of this study was to determine the natural progression of spinal schwannomas and establish the risk of tumor growth.
  
  
  METHODS
  This study retrospectively analyzed data from 23 patients (12 men and 11 women, 40-89 years old) with schwannomas detected by MRI. The mean follow-up period was 5 years (range 2-10 years). The absolute and relative growth rates of the tumors were calculated.
  
  
  RESULTS
  The average tumor size was 1495 mm(3) at the initial visit and 2224 mm(3) at the final follow-up. The average absolute growth rate was 139 mm(3) per year, and the average relative growth rate was 5.3% per year. Tumors were classified into 3 groups based on enhancement patterns: isointense/hyperintense (iso/high; 11 cases), rim enhancement when enhancement was peripheral (high/rim; 5 cases), and heterogeneous/heterogeneous (hetero/hetero; 7 cases) based on Gd-enhanced T2-weighted MRI. The average absolute growth rates of the 3 lesion groups were 588 mm(3), 957 mm(3), and 3379 mm(3), respectively (p < 0.01).
  
  
  CONCLUSIONS
  Although the tumors classified as iso/high and high/rim on T2-weighted Gd-enhanced MR images were small and grew very little, most tumors with hetero/hetero classification increased in size. Hetero/hetero-type tumors should be followed closely and may require surgery.
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Ando
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Imagama
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Zenya
authors.initials: Z
authors.lastname: Ito
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Yagi
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Hida
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Kenyu
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Mikito
authors.initials: M
authors.lastname: Tsushima
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Yoshimoto
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods; D009442:Neurilemmoma / Q000175:diagnosis / Q000601:surgery; D012189:Retrospective Studies; D013125:Spinal Neoplasms / Q000473:pathology* / Q000601:surgery*
keywords: JOA = Japanese Orthopaedic Association; SCH = schwannoma; T1W = T1-weighted; T2W = T2-weighted; intradural extramedullary tumors; natural progression; oncology; spinal schwannomas