Neurilemmomas of the extremities are nerve sheath tumors involving peripheral nerves of the extremities. We analyzed MR images of 16 surgically proved tumors in 12 patients and compared the MR images with gross pathologic specimens in two tumors
(2/16).
Spin echo T1-weighted images were obtained in all the patients but T2-weighted images were obtained in six patients with a gradient echo technique. Gadolinium dimeglumine enhanced T1-weighted images were obtained in 11 patients (15/16). Signal
on
T1-weighted images was iso or slightly higher than that of the adjacent muscles. Signal on T2-weighted images ranged from homogeneous high to heterogeneous. After Gadolinium injection, all the 15 tumors showed enhancement. Small sized tumors were
enhanced homogeneously but there was a tendency tobe enhanced heterogeneously to the central portion with peripheral rim enhancement as the size of the tumors increased. Pathologically, the enhanced portion was correlated the with solid protion
was
correlated the with solid portion of the tumors. Also encapsulation of the mass (12/16), suspended nerve strings (9/16) and bony erosion (1/16) were detected.
MR characteristics of neurilemmoma include heterogeniety on enhanced T1 and T2 weighted images, encapsulation, and suspended nerve strings. Signal heterogeneity on enhanced T1 and T2 weignted images may be attributed to the variable cellularity,
cystic
changes, vascularity and focal hemorrhage of the tumors
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