Orbital schwannomas: findings from magnetic resonance imaging in 62 cases

Abstract

Purpose To evaluate the diagnostic value of magnetic resonance imaging (MRI) and illustrate the common MRI features of orbital schwannoma. Methods We reviewed 62 consecutive cases of pathologically proven orbital schwannoma investigated by MRI. All cases were examined using T1-and T2-weighted images. Enhanced T1-weighted images were obtained after administration of gadopentetate dimeglumine. The images were analysed and compared. Results Cone-shaped lesions were the most frequent (16, 26%), followed by dumbbell-shaped (10, 16%), oval (9, 15%) and round lesions (8, 13%). The most common site was the superior aspect of the orbit (17, 27%), followed by the medial superior (12, 19%) and the orbital apex (12, 19%). On unenhanced T1-weighted images, 53 (85%) lesions showed isointensity or small patches of hypointensity. The patterns of enhancement seen on T1-weighted images correlated with the signal characteristics of unenhanced T2-weighted images. Five patterns emerged in our series. Among these patterns, the most common sign, found in 18 (29%) cases, was peripheral (ring) enhancement on enhanced T1-weighted images, which showed peripheral isointensity with central hyperintensity on T2-weighted images. Lesions with homogeneous or heterogeneous enhancement were seen in 16 (26%) and 26 (42%) cases, respectively. Conclusions MRI is a valuable diagnostic method for orbital schwannoma, particularly when contrast is applied. The locations and shapes of tumours can be seen distinctly. T1-weighted images are relatively nonspecific. T2-weighted and enhanced T1-weighted images provide information about the pathology of tumours. In particular, peripheral enhancement should be considered a target sign of schwannoma.

Value of MR Imaging in Differentiation between Solitary Fibrous Tumor and Schwannoma in the Orbit

“…11 Moreover, recurrence and malignant transformation of orbital SFTs occur more often than in schwannomas. 2,6,[11][12][13][14][15] Therefore, it is important to differentiate SFTs from schwannomas and other orbital tumors before treatment recommendations are made. Orbital schwannoma, constituting 1% of all orbital tumors, is more common than SFT.…”

“…7 Despite the distinct histologic and immunohistochemical appearance of SFT, its imaging appearance in the orbit has been considered nonspecific and it has often been misdiagnosed as schwannoma. 8,9 Nonetheless, the prognosis and treatment of SFT and schwannoma in the orbit are different, 2,6,[10][11][12][13][14][15] and distinguishing SFT and schwannoma in the orbit is important because SFT is a more aggressive lesion than schwannoma. SFTs are richly vascular with many dilated vessels.…”

Orbital schwannoma: a clinicopathologic study

“…A variety of bony changes were seen in our cases including bone erosion, superior orbital fissure widening, massive generalized orbital expansion, fossa formation and excavation of the orbital walls to the extent that the tumor herniated into the maxillary sinus and nasal cavity. There have been a few reports on MRI findings of orbital schwannoma and their correlation with histopathological findings [6,12,16] ( Table 1). Wang et al [6] in their study described five patterns of presentation of orbital schwannomas on MRI showing the anatomical variability inherent in these lesions.…”

“…There have been a few reports on MRI findings of orbital schwannoma and their correlation with histopathological findings [6,12,16] ( Table 1). Wang et al [6] in their study described five patterns of presentation of orbital schwannomas on MRI showing the anatomical variability inherent in these lesions.…”

“…Orbital schwannomas usually arise from the sensory branches of the ophthalmic division of the trigeminal nerve. The supraorbital and supratrochlear nerves are commonly affected, and hence, superior orbit is commonly involved [5,6]. Less commonly, a schwannoma may develop from one of the motor nerves such as the oculomotor or ciliary nerve.…”