Differentiation between schwannomas and neurofibromas in the extremities and superficial body: the role of high-resolution and color Doppler ultrasonography.
OBJECTIVE
The purpose of this study was to verify whether high-resolution and color Doppler ultrasonography could distinguish schwannomas from neurofibromas.


METHODS
Seventy-six tumors in 71 patients were included in this study. There were 46 patients (50 tumors) with schwannomas and 25 patients (26 tumors) with nondiffuse neurofibromas in the extremities or superficial parts of the body. Ultrasonographic examinations were performed in all patients. The tumor size, shape, location, internal echogenicity, posterior acoustic phenomenon (eg, shadowing or enhancement), capsule, relationship with the adjacent nerve, and presence of cystic components were documented. Color Doppler studies (75 lesions) and spectral Doppler studies (44 lesions) were performed. All data were analyzed with statistical software to check the significance.


RESULTS
Both tumors presented as well-defined hypoechoic nodules on ultrasonography. They were oval or lobulated, showed posterior acoustic enhancement, and were hypervascular on color Doppler ultrasonography. There was no significant difference with respect to ultrasonographic morphologic characteristics. The rates of centric, eccentric, and undetermined associations with nerves were 40%, 20%, and 40% in the schwannomas and 46.2%, 0%, and 53.8% in the neurofibromas, respectively, showing a significant difference (P = .032). There was no significant difference in the chance of cystic changes between the schwannomas (30%) and neurofibromas (23%).


CONCLUSIONS
No ultrasonographic finding (gray scale, color Doppler, or spectral analysis) allows differentiation between neurofibromas and schwannomas of the extremities. A nerve eccentrically entering a mass was seen only in schwannomas, and that may allow differentiation between neurofibromas and schwannomas.
Tsai
Wan-Chen
WC
Department of Radiology, Taipei Veterans General Hospital, Taiwan.
Chiou
Hong-Jen
HJ
Chou
Yi-Hong
YH
Wang
Hsin-Kai
HK
Chiou
See-Ying
SY
Chang
Cheng-Yen
CY
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003937:Diagnosis, Differential; D005121:Extremities / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000000981:diagnostic imaging*; D009455:Neurofibroma / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D018615:Ultrasonography, Doppler, Color