Frontotemporal giant extradural dermoid cyst: illustrative case

Area of Science:

• Neurosurgery
• Radiology
• Oncology

Background:

• Dermoid cysts are rare, typically benign tumors often found along the midline.
• While usually presenting with normal lab results and typical imaging, some cases exhibit atypical features leading to misdiagnosis.

Purpose of the Study:

• To highlight the diagnostic challenges and key features of an extremely rare extradural dermoid cyst with a mural nodule.
• To emphasize the importance of recognizing atypical radiological signs and utilizing tumor markers for accurate diagnosis.

Main Methods:

• Case presentation of a 58-year-old patient with neurological symptoms including tinnitus, dizziness, and gait unsteadiness.
• Utilized computed tomography (CT) and magnetic resonance imaging (MRI) to evaluate an intracranial lesion.
• Assessed serum levels of carbohydrate antigen 19-9 (CA19-9).
• Performed surgical resection and confirmed diagnosis via histological examination.

Main Results:

• The patient presented with neurological symptoms and significantly elevated serum CA19-9 levels (186 U/mL).
• CT revealed a hypodense extradural lesion with a hyperdense mural nodule in the left frontotemporal region.
• MRI showed mixed signal intensity on T1- and T2-weighted imaging.
• Histopathology confirmed the diagnosis of dermoid cyst; no recurrence was noted at 9-month follow-up.

Conclusions:

• Extradural dermoid cysts with mural nodules are exceptionally rare intracranial tumors.
• Atypical imaging features (hypodense lesion, mixed T1/T2 signals, mural nodule) in extradural locations should raise suspicion for dermoid cysts.
• Combining elevated serum CA19-9 with atypical radiological findings can improve diagnostic accuracy and prevent misdiagnosis.