Orbital Frontal Nerve Schwannoma—Distinctive Radiological Features

• Published in: American journal of ophthalmology Vol. 186; pp. 41 - 46
• Main Authors: Young, Stephanie Ming, Kim, Yoon-Duck, Jeon, Gang Seok, Woo, Kyung In
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2018; Elsevier Limited
• Subjects: Adult; Calcification; Diagnosis, Differential; Female; Follow-Up Studies; Humans; Magnetic Resonance Imaging - methods; Male; Medical imaging; Middle Aged; Neoplasm Staging - methods; Neurilemmoma - diagnosis; Neurilemmoma - surgery; NMR; Nuclear magnetic resonance; Ophthalmic Nerve - diagnostic imaging; Ophthalmologic Surgical Procedures; Ophthalmology; Orbit - diagnostic imaging; Orbit - innervation; Orbital Neoplasms - diagnosis; Orbital Neoplasms - surgery; Patients; Prognosis; Retrospective Studies; Time Factors; Tomography, X-Ray Computed - methods; Tumors; United States > US
• ISSN: 0002-9394; 1879-1891
• DOI: 10.1016/j.ajo.2017.11.012

To review the radiological findings of frontal nerve schwannoma of the orbit and determine distinguishing imaging features. Retrospective interventional case series. Setting: Single tertiary institution. Period: September 1996 to December 2016. Patient Population: Thirteen patients with orbital frontal nerve schwannoma. Intervention: Patients underwent surgical excision following preoperative imaging. Main Outcome Measures: Imaging characteristics on computed tomography (CT) and magnetic resonance imaging (MRI). There were 13 patients with histopathologically proven schwannoma of the frontal nerve. Mean age was 44.4 years and 61.5% were male. The majority (84.6%) of frontal nerve schwannomas extended between the supraorbital notch and superior orbital fissure. The most common shape seen in our patients with frontal nerve schwannoma was a multilobulated “beaded” appearance (46.2%), followed by a dumbbell (30.8%), oval (15.4%), and fusiform (7.7%) shape. On CT imaging, all patients had bony remodeling. Target sign, fascicular sign, and cystic degeneration were seen in 76.9%, 35.8%, and 46.2% of patients, respectively. On radiological-pathologic correlation, the zone of tightly packed cellular solid portion (Antoni A pattern) corresponded to the hypointense area on T2-weighted MRI and the hyperintense area on gadolinium-enhanced T1-weighted MRI. Frontal nerve schwannoma should be considered as a differential diagnosis for any superior orbital mass. Our study describes several radiological findings that would point toward its diagnosis, including its multilobulated beaded or dumbbell shape, as well as additional signs such as the target sign, fascicular sign, and cystic degeneration.