Insular and Sylvian Fissure Dermoid Cyst with Giant Cell Reactivity: Case Report and Review of Literature

Dermoid cysts are rare intracranial tumors that are most commonly found infratentorially and along the midline. Characterized by slow growth and often found incidentally, these lesions can nonetheless have severe complications, notably rupture leading to chemical meningitis. They infrequently present as a supratentorial and lateralized mass. As such, sylvian fissure dermoid cysts are exquisitely rare. We present a rare case of a dermoid cyst with giant cell reactivity suggestive of focal rupture and chronic inflammation.

A 61-year-old female presented with new-onset seizures. Magnetic resonance imaging revealed a right insular mass measuring 4.3 × 4.5 cm with compression of the ipsilateral frontal and temporal lobes. The mass was nonenhancing; however, it was bright on diffusion-weighted imaging, suggesting a dermoid cyst. She underwent craniotomy for tumor resection. Histologic analysis revealed keratinizing squamous epithelium, sebaceous glands, and hair follicles associated with giant cell reaction involving the capsule of the cyst consisted with dermoid cyst. At 2.5 years post operation, she is seizure free and without evidence of recurrence.

The dermoid cyst in our patient was not grossly ruptured, but histopathologic analysis revealed giant cell reactivity, which may indicate focal rupture or chronic inflammation. The relationship between rupture of dermoid cysts and inflammation is not well elucidated. It is not known whether symptoms occur immediately after rupture or as an acute manifestation of a chronic process following rupture. As these lesions are quite rare and rupture is even rarer, more diligence on our part regarding details of histopathology for dermoid cysts is necessary.