Frontal nerve schwannoma in a 16-year-old girl presenting with a rapid growth for 2 years.

Background: Orbital schwannomas arising from the frontal nerve are a rare but distinct entity.

Case description: A 16-year-old girl presented to our hospital with gradually progressive proptosis. Computed tomography (CT) performed 2 years ago incidentally detected a retrobulbar mass in the left orbit measuring 13 mm × 14 mm × 10 mm, which was not identified on CT performed at the age of 4 years. CT taken at presentation revealed marked tumor growth over 2 years, measuring 24 mm × 20 mm × 17 mm. On magnetic resonance imaging (MRI), the tumor appeared homogeneously isointense both on the T1- and T2-weighted sequences. The patient underwent transcranial tumor resection. Following unilateral frontal craniotomy, an osteotomy was made to the left anterior fossa floor. On reflecting, the periorbita revealed the frontal nerve with the proximal segment intermingled with the tumor. The levator and superior rectus muscles were flattened and located immediately beneath the tumor. A gross total resection was performed. Microscopic findings of the resected tumor were consistent with schwannoma.

Conclusion: Frontal nerve schwannomas may grow rapidly under certain conditions. Periodic follow-up using MRI and timely resection is recommended when an asymptomatic orbital tumor, possibly a frontal nerve schwannoma, is detected in young patients.