Histologic assessment of peritumoral edema in soft tissue sarcoma.
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.
White
Lawrence M
LM
Department of Medical Imaging, Mt. Sinai Hospital and Princess Margaret Hospital, University of Toronto, Toronto, ON, Canada. lwhite@mtsinai.on.ca
Wunder
Jay S
JS
Bell
Robert S
RS
O'Sullivan
Brian
B
Catton
Charles
C
Ferguson
Peter
P
Blackstein
Martin
M
Kandel
Rita A
RA
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*
D003287:Contrast Media; D005682:Gadolinium