Translamina Terminalis Approach for Resection of a Suprasellar Epidermoid Cyst with Third Ventricular Extension

Epidermoid cysts are benign, cystic lesions filled with keratin and lined with stratified squamous epithelium. Typically, epidermoid cysts are located in the cerebellopontine angle and less frequently in the sellar/suprasellar region. Traditionally, transcranial approaches have been utilized to resect these lesions but with advancements in endoscopy, endoscopic endonasal approaches have been increasingly described. Case reports have described epidermoid cysts, arising from the pituitary stalk in the suprasellar region and resected via an endoscopic endonasal approach. We describe a suprasellar epidermoid cyst with rare predominant extension into the third ventricle. An open pterional craniotomy and unilateral subfrontal approach through the lamina terminalis was performed to resect this lesion in its entirety.

A 58-year-old male presented with worsening headaches, vision, and memory over 2-month duration. Magnetic resonance imaging revealed a T1 hyperintense and T2 hypointense 2.1 × 1.8 × 2.6 cm suprasellar lesion with areas of diffusion restriction ([Fig. 1]), causing superior displacement of the optic chiasm. The most likely diagnosis was an epidermoid cyst. Neuro-ophthalmology evaluation demonstrated bitemporal hemianopsia, worse in the left eye. Endocrinology testing showed mildly elevated prolactin of 51.7 ng/mL, likely due to stalk effect. Surgery was recommended, given his visual deficits. Due to significant extension of the lesion into the third ventricle, an open approach was favored over an endoscopic endonasal approach. The patient subsequently underwent a right-sided pterional craniotomy and trans-lamina terminalis approach to the lesion. After a subfrontal approach to the suprasellar region, the opticocarotid cistern was opened to facilitate brain relaxation, followed by careful dissection to expose the optic chiasm, and lamina terminalis, arising off its dorsal aspect without use of retractors. The lamina terminalis was then opened through a combination of electrocautery and sharp and blunt dissection, revealing a keratin-laden, white flaky lesion consistent with an epidermoid cyst ([Fig. 2]). The lesion was removed in its entirety via piecemeal resection ([Fig. 3]).

The patient's post-operative course was notable for a mild left homonymous hemianopsia, likely from right optic tract manipulation that persisted at one-month follow-up with plans for further neuro-ophthalmology evaluation. He was also started on prednisone for low post-operative cortisol levels of 4.0 μg/dL with plans to taper as an outpatient.

Transcranial approaches through the lamina terminalis for third ventricular lesions have predominantly been described in craniopharyngiomas. While patterns of lesion growth can vary to involve the floor of the third ventricle or superiorly through the foramen of Monroe in the lateral ventricles, those that are centered along the anterior wall of the third ventricle may be particularly amenable to the trans-lamina terminalis approach, as evidenced in this case. While the endoscopic endonasal approach may be suitable for most sellar and suprasellar epidermoid cysts, those with predominant third ventricular extension may be limited by an excessively long surgical corridor, which may limit the resection. This case translates surgical experience of open trans-lamina terminalis approaches for third ventricular tumors to rare instances of suprasellar epidermoid cysts predominantly involving the anterior portion of the third ventricle and may facilitate gross total resection compared with endoscopic options.

Fig. 1 Pre-operative MRI. (A) Sagittal and (B) coronal T1-weighted post-contrast MRI demonstrate an enhancing suprasellar lesion with anterior third ventricular extension that (C) showed diffusion restriction on DWI, consistent with epidermoid cyst.

Fig. 2 Intra-operative microscopic photos. (A) Blunt dissection of the lamina terminalis along the posterior dorsal aspect of the optic chiasm is performed (arrow). (B) The lamina terminalis is opened and the epidermoid cyst is visualized (arrow), (C) which was resected piecemeal (arrow). (D) A de-magnified view of the operative field is shown after resection. Abbreviations: FL (frontal lobe), OC (optic chiasm), ICA (internal carotid artery), CN3 (cranial nerve 3).

Fig. 3 Two-month post-operative MRI. (A) Sagittal and (B) coronal T1-weighted post-contrast MRI demonstrate gross total resection of the suprasellar lesion with (C) absence of diffusion restriction on DWI to suggest any residual.

Publication History

Article published online:
15 February 2022