Extraaxial Neurofibromas Versus Neurilemmomas: Discrimination with MRI

Abstract

MRI shows features helpful for differentiating extraaxial neurofibromas from neurilemmomas; however, no single finding or combination of findings allows definitive differentiation.

Correlation of Magnetic Resonance Imaging Findings of Spinal Intradural Extramedullary Schwannomas with Pathologic Findings

“…However, in our study, none of the cases showed the target sign, which was probably related to the frequent cystic changes in schwannomas that were intradural extramedullary in location. The fascicular sign manifests as multiple small ring-like structures with a high signal intensity in the background on T2-weighted images, and is more frequently observed in schwannomas than in neurofibromas (2). Only four cases in our study (23.52%) showed the fascicular sign, but it was not as definite as that in their peripheral counterparts.…”

“…2). The target sign was described in T2-weighted MRI findings of neurogenic tumors (2,8), which was characterized by a low signal intensity centrally and a high signal intensity peripherally, and it was seen more frequently in neurofibromas (50-70%) than in schwannomas (50%) (2). However, in our study, none of the cases showed the target sign, which was probably related to the frequent cystic changes in schwannomas that were intradural extramedullary in location.…”

“…Previous studies reported that schwannomas arising from peripheral nerves frequently present with a fusiform appearance, encapsulation, the target sign (intratumoral peripheral rim of high signal intensity on a T2-weighted image), and the fascicular sign (small ring-like intermediate, low signal intensities with background high signal intensity on a T2-weighted image) on magnetic resonance imaging (MRI) (1,2). Cystic changes and necrosis can occur, especially in deep-seated large schwannomas of long duration called ancient schwannomas (3).…”

Imaging findings of neurogenic tumours in the head and neck region

“…Jee et al 15 reported that the presence of target signs on T 2 WIs suggests a high probability of neurofibromatosis, although a fascicular appearance and thin hyperintense rim were also detected in some cases. On the other hand, Koga et al 12 suggested that the target sign predominantly suggests the possibility of a schwannoma.…”

Haemorrhagic low-grade fibromyxoid sarcoma: MR findings in two young women

“…Fibromatosis is usually hypointense on T 2 weighted images but may also show heterogeneous hyperintensity, reflecting marked cellularity or myxoid tissue. Neurogenic tumours are characterised by the entry and exit of nerves [11].…”