Differentiation between neurofibromas and malignant peripheral nerve sheath tumors in neurofibromatosis 1 evaluated by MRI.
OBJECTIVE
The imaging discrimination between neurofibroma (NF) and malignant peripheral nerve sheath tumor (MPNST) is clinically very important. The purpose of this study is to define the criteria for the differential diagnosis between NF and MPNST on MRI in neurofibromatosis 1 (NF1).


METHODS
A total of 37 patients with NF1, 18 NFs and 19 MPNSTs were evaluated by MRI at 1.5 T. Magnetic resonance imaging (MRI) findings were compared using univariate and multivariate analyses.


RESULTS
The MRI findings characteristic of MPNST (p < 0.05) were an irregular tumor shape (15/19 in MPNST vs. 5/18 in NF), unclear margin (13/19 in MPNST vs. 6/18 in NF), intra-tumoral lobulation (12/19 in MPNST vs. 3/18 in NF), presence of high signal-intensity area on T1-weighted images (T1WI) (12/19 in MPNST vs. 1/18 in NF), no target sign (0/19 in MPNST vs. 12/18 in NF), inhomogeneous enhancement on contract-enhanced T1WI (17/18 in MPNST vs. 9/16 in NF) and a lower rate of enhanced area (54% in MPNST vs. 87% in NF) were critical indicators to differentiate MPNST from NF. A multivariate analysis showed that intra-tumoral lobulation and the presence of a high signal-intensity area on T1WI were considered to be diagnostic indicators of MPNST. The sensitivity and specificity for these two items were 63.2, 83.3, 63.2 and 87.5%, respectively.


CONCLUSIONS
MRI shows features which were helpful for differentiating MPNST from NF.
Matsumine
Akihiko
A
Department of Orthopaedic Surgery, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan. matsumin@clin.medic.mie-u.ac.jp
Kusuzaki
K
K
Nakamura
T
T
Nakazora
S
S
Niimi
R
R
Matsubara
T
T
Uchida
K
K
Murata
T
T
Kudawara
I
I
Ueda
T
T
Naka
N
N
Araki
N
N
Maeda
M
M
Uchida
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D005682:Gadolinium; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018317:Nerve Sheath Neoplasms / Q000175:diagnosis*; D009455:Neurofibroma / Q000175:diagnosis*; D009456:Neurofibromatosis 1 / Q000175:diagnosis*; D010524:Peripheral Nervous System Neoplasms / Q000175:diagnosis*; D011868:Radioisotopes; D014055:Tomography, Emission-Computed / Q000379:methods; D055815:Young Adult
D011868:Radioisotopes; D005682:Gadolinium