Out-of-third ventricle colloid cysts: review of the literature on pathophysiology, diagnosis and treatment of an uncommon condition, with a focus on headache.

Colloid cysts are rare benign intracranial lesions classically described as "third ventricle colloid cysts" because of their location within the third ventricle. These lesions' clinical and diagnostic features are mainly related to intermittent or persistent obstruction of foramina of Monro causing cerebrospinal fluid (CSF) circulation impairment and symptoms of raised intracranial pressure. Few reports on colloid cysts located outside the third ventricle have been published over the years. This paper aims to review the existing literature on out-of-third ventricle colloid cysts, and introduces a new illustrative case of lateral ventricle colloid cyst surgically managed with endoscopic technique.