MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas.
OBJECTIVE
The objective of this study was to identify the MRI criteria that best differentiate malignant peripheral nerve sheath tumors from benign neurofibromas.


METHODS
We retrospectively analyzed MR images obtained for 41 histologically diagnosed cases of malignant peripheral nerve sheath tumor and 20 cases of neurofibroma that had been treated at four tertiary institutions. Twenty of the patients with malignant peripheral nerve sheath tumors and 14 patients with neurofibromas developed the disease in association with neurofibromatosis 1. The MR images were evaluated with regard to tumor size, signal intensity, heterogeneity of T1- and T2-weighted MR images, enhancement pattern, definition of margins, presence of perilesional edemalike zone, and presence of intratumoral cystic lesions.


RESULTS
Significant differences between malignant peripheral nerve sheath tumors and neurofibromas were noted for the largest dimension of the mass, peripheral enhancement pattern, perilesional edemalike zone, and intratumoral cystic lesion. In cases associated with neurofibromatosis 1, heterogenicity on T1-weighted images was also significant in differentiating neurofibroma from malignant peripheral nerve sheath tumor. The presence of two or more of the four features suggestive of malignancy indicated malignant peripheral nerve sheath tumor with a sensitivity of 61% and a specificity of 90%.


CONCLUSIONS
The MR features described in this study are useful for distinguishing malignant peripheral nerve sheath tumors from neurofibromas. If a tumor has two or more of the four statistically significant features, it can be considered to be highly suspicious of malignancy and should be subjected to a biopsy for early diagnosis.
Wasa
Junji
J
Department of Orthopaedic Surgery, Nagoya University Graduate School and School of Medicine, Showa, Nagoya 466-8550, Japan.
Nishida
Yoshihiro
Y
Tsukushi
Satoshi
S
Shido
Yoji
Y
Sugiura
Hideshi
H
Nakashima
Hiroatsu
H
Ishiguro
Naoki
N
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018317:Nerve Sheath Neoplasms / Q000175:diagnosis* / Q000473:pathology; D009455:Neurofibroma / Q000175:diagnosis / Q000473:pathology; D009456:Neurofibromatosis 1 / Q000473:pathology*; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
D003287:Contrast Media