title: Histologic assessment of peritumoral edema in soft tissue sarcoma.
abstract: OBJECTIVE
  To evaluate whether satellite tumor cells can be identified histologically in the tissues surrounding a soft tissue sarcoma and whether their presence correlates with increased T(2)-weighted signal intensity on MRI.
  
  
  METHODS
  Fifteen patients with a high-grade extremity or truncal soft tissue sarcoma underwent preoperative MRI. The extent of high T(2)-weighted signal changes in the tissues surrounding tumor, thought to represent peritumoral edema/reactive changes, was determined. Twelve patients received i.v. gadolinium, and contrast enhancement was determined. All patients underwent surgical resection in the absence of preoperative chemotherapy or radiotherapy. The presence of tumor cells in the surrounding tissues was determined histologically in representative paraffin-embedded sections and correlated with the MRI findings.
  
  
  RESULTS
  The extent of peritumoral T(2)-weighted MRI signal changes ranged from 0 to 7.1 cm (mean, 2.5 cm); contrast enhancement ranged from 0 to 5.3 cm (mean, 1.1 cm). Sarcoma cells were identified histologically in the tissues beyond the tumor in 10 of 15 cases. In 6 cases, tumor cells were located within 1 cm of the tumor margin, and in 4 cases, malignant cells were found at a distance >1 cm and up to a maximum of 4 cm. The location of tumor cells beyond the margin did not correlate with tumor size nor did it correlate with the location or extent of peritumoral changes.
  
  
  CONCLUSIONS
  The ability to identify tumor cells beyond the margin of a soft tissue sarcoma has important implications in planning appropriate targets for treatment. This could influence the use of new radiotherapy technologies such as intensity-modulated radiotherapy that aim to minimize treatment volumes through conformal planning.
authors.affiliation: Department of Medical Imaging, Mt. Sinai Hospital and Princess Margaret Hospital, University of Toronto, Toronto, ON, Canada. lwhite@mtsinai.on.ca
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: White
authors.forename: Jay S
authors.initials: JS
authors.lastname: Wunder
authors.forename: Robert S
authors.initials: RS
authors.lastname: Bell
authors.forename: Brian
authors.initials: B
authors.lastname: O'Sullivan
authors.forename: Charles
authors.initials: C
authors.lastname: Catton
authors.forename: Peter
authors.initials: P
authors.lastname: Ferguson
authors.forename: Martin
authors.initials: M
authors.lastname: Blackstein
authors.forename: Rita A
authors.initials: RA
authors.lastname: Kandel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D004487:Edema / Q000473:pathology*; D005260:Female; D005682:Gadolinium; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D018365:Neoplasm, Residual; D012509:Sarcoma / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000473:pathology*
chemical_list: D003287:Contrast Media; D005682:Gadolinium