When is pre-operative imaging required for craniofacial dermoid cysts/sinuses? A review

Objectives Dermoid cysts/sinuses (DCS) are congenital masses occurring along lines of embryonic fusion. Midline DCS carry a risk of intracranial extension. Pre-operative computed tomography (CT) or magnetic resonance imaging (MRI) are the primary imaging modalities used and based on the results, the need to involve a neurosurgical team in the resection is determined. Although less so, non-midline locations are also at risk for intracranial communication. This study aims to quantify our institutional experience with both midline and lateral DCS for intracranial extension and discuss potential need for preoperative imaging in all DCS cases. Methods Institutional Review Board approval was obtained. Pediatric patients ages 0–18 years with DCS presenting to the pediatric otolaryngology, plastic surgery, and neurosurgery clinics from 2005 to 2020 were retrospectively reviewed. Data collected included patient demographics, imaging modality, location, size, complications, and presence/absence of intracranial extension. DCS location included nasoethmoidal (NE), periorbital, frontotemporal (FT), and scalp. Lesions were further classified as midline and non-midline. Results 205 patients with surgically removed DCS were included for analysis. Mean age at surgery was 3 years. MRI was the most common imaging modality used (60.5%), followed by US (18%), CT (18%) and plain films (1%). Locations were: NE (69, 34%), periorbital (67, 33%), FT (28, 14%), and scalp (41, 20%). 105 DCS were midline: NE (69), periorbital (7), and scalp (29). Of these, 29 (28%) had intracranial extension: NE (8), scalp (21). 100 DCS were non-midline: periorbital (60), FT (28) and scalp (12). Of these, 7 (7%) had intracranial extension: periorbital (3), FT (3) and scalp (1). Conclusion The risk of intracranial extension of midline craniofacial DCS is well established. We have shown that there is a percentage of lateral DCS which carry a risk for intracranial extension, and for which the involvement of a neurosurgical team may be required. Given the potential benefit, pre-operative imaging of all lateral head and neck DCS may be prudent to screen for intracranial extension.