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Retrocerebellar Ependymal Cyst Presenting with Obstructive Hydrocephalus in an Infant

Intracranial ependymal cysts (ECs) are rare benign lesions. They are frequently asymptomatic and arise in the supratentorial regions. Retrocerebellar ECs is a rare location. We present a case of 3-months-old infant who developed obstructive hydrocephalus, bulging fontanel, and macrocephaly secondary to a retrocerebellar EC. Magnetic resonance imaging (MRI) showed a large retrocerebellar cyst that compressed the cerebellum and the brainstem, producing fourth ventricle outlet obstruction and supratentorial hydrocephalus. Microsurgical fenestration of the cyst to the obex of the fourth ventricle and a cystic wall biopsy were performed. The procedure improved supratentorial hydrocephalus, as well as the patient's clinical condition. A histopathological study confirmed the diagnosis of an EC.As far as we know, after a thorough review of the literature, this is the first reported case of retrocerebellar EC. It is a rare cause of hydrocephalus due to outlet obstruction of the fourth ventricle. Treatment of the cause itself has been shown to be effective.