Extradural Dermoid Cyst of the Cerebellar Convexity in an Elderly Patient: A Rare Case

Dermoid cysts (DCs) are rare tumours originating from ectodermal and mesodermal tissues.They usually occur in the midline, especially in the posterior fossa.In this study, we describe an interesting case of a 73year-old patient who presented with mild headaches, an imbalanced gait, and a slow, progressive hearing loss in the left ear.A brain CT scan showed a hypodense left cerebellar convexity extra-axial mass, containing some calcifications and causing bone erosion.On MRI, this tumour had a low T1 signal, a heterogeneous T2 signal, and a heterogeneous signal on diffusion-weighted images, with discrete peripheral enhancement.The patient was operated on through a left retrosigmoid approach, during which a yellowish, soft, waxy extra-dural mass was removed.Post-operative follow-up was uneventful.Histological study found stratified keratinized tissue, and tumour walls were covered with Malpighian epithelium.These tumours usually have slow, progressive symptoms depending on location; however, severe, life-threatening presentations are possible.CT scan and MRI are useful to establish the diagnosis of dermoid cysts.Maximal safe resection is the treatment of choice.