Ruptured intracranial dermoid cyst as an incidental finding: Case report.

Intracranial dermoid cysts are rare, benign congenital lesions originating from ectodermal remnants. Though typically asymptomatic, their rupture, although infrequent, can lead to significant neurological complications, such as chemical meningitis, vasospasm, and hydrocephalus. Imaging with computed tomography (CT) and magnetic resonance imaging (MRI) plays a crucial role in diagnosis, providing characteristic features related to the high lipid content of these lesions. An 86-year-old female presented with a 3-day history of headache, nausea, vomiting, and facial cellulitis after an arthropod bite. Concern that the facial cellulitis might have progressed and involved deeper structures prompted imaging studies. Non-contrast CT revealed an incidental ruptured pericallosal dermoid cyst with lipid material in the ventricular system. MRI confirmed the rupture, showing hyperintense lesions on T1-weighted sequences. Cerebrospinal fluid analysis indicated aseptic meningitis. The patient has been diagnosed with herpes zoster-related meningoencephalitis. Despite their rarity, ruptured intracranial dermoid cysts remain challenging due to their complex presentation. Early identification through advanced imaging is essential for guiding appropriate intervention. While complete resection is the goal, subtotal excision can be indicated when the cyst capsule adheres to critical neurovascular structures, given the low risk of recurrence and malignant transformation.