Intracerebellar extension of occipital scalp dermoid after initial resection: illustrative case

Abstract

Background: Dermoid cysts are benign ectodermal growths that commonly form at cranial sutures. Although benign, resection is often recommended to prevent intracranial extension as the cyst grows. The prognosis after resection is very good, provided a complete resection is possible.

Observations: The authors present the case of a 10-month-old male patient with an occipital scalp dermoid cyst with intracranial extension who underwent subtotal resection and later presented with cerebellar extension.

Lessons: Scalp dermoid cysts with intradiploic extension have a significant risk of intracranial extension. Thus, care must be taken to achieve total resection in the first attempt or provide close follow-up before intracranial extension develops. https://thejns.org/doi/10.3171/CASE2548.

Keywords: hydrocephalus; intracranial dermoid cyst; pediatrics.

FIG. 1.

Posterior scalp ultrasound showing possible dermoid cyst (red arrow) with subtle inferior extension (purple arrow) into the underlying occipital bone (blue arrows).

FIG. 2.

Axial (A and C) and sagittal (B) T2-weighted MR images obtained during follow-up, demonstrating midline cerebellar lesion with secondary supratentorial ventriculomegaly. Axial diffusion-weighted MR image (D) showing diffusion restriction in the dense posterior portion of the lesion consistent with a dermoid mass.

FIG. 3.

Under 3D exoscope visualization, the intradiploic stalk is visualized (A; arrow). The cyst is grossly observed to have a tan color with flecks of brown (B; arrow), with internal epidermoid features such as visible hair (C; arrow) characteristic of a dermoid cyst. Postresection cavity is observed following gross-total resection (D).

FIG. 4.

Postoperative axial (A and C) and sagittal (B) T2-weighted MR images showing total resection of the dermoid cyst with some immediate resolution of ventriculomegaly. Diffusion-weighted axial MR image (D) showing decreased diffusion restriction compared with the preoperative image.

FIG. 5.

Axial (A and C) and sagittal (B) T2-weighted MR images obtained at the most recent 3-month clinical follow-up, showing decreased size of the resection cavity and resolution of the ventriculomegaly. Diffusion-weighted axial MR image (D) showing decreased diffusion restriction compared with the preoperative image.