[«De novo» development of a suprasellar arachnoid cyst].

Intracranial arachnoid cysts are fluid-filled cavities that arise within the cranial arachnoid, representing approximately 1%-2% of all intracranial lesions among the paediatric population. We present the case of a 2-year-old boy who presented with instability and episodes of ocular deviation. A computed tomography scan (CT scan) and magnetic resonance imaging (MRI) of the brain revealed a suprasellar cyst and obstructive hydrocephalus. At birth a transfontanellar ultrasound was normal. The cyst underwent endoscopic fenestration with complete remission of symptoms. In the review of the literature, we found only 6 previous cases of an intracranial arachnoid cyst whose origin was not clearly congenital or traumatic, and ours is the second case of a suprasellar arachnoid cyst to arise de novo. The clinical features, imaging characteristics and treatment of the previously reported cases are discussed.