Cyst refers to an abnormal growth of benign cells, typically containing normal cerebrospinal fluid. Central nervous system cysts may occur as neoplasms or subsequent to leptomeningitis, hemorrhage, or surgery. Most patients presenting with cyst are asymptomatic, though headache, calvarial bulging, intracranial hypertension, craniomegaly, developmental delay, visual loss, precocious puberty, and seizures, with focal neurologic signs can occur. Additional cognitive consequences may include symptoms of dementia and inattention, depending on cyst loci (e.g., parietal lobe cysts have been associated with dementia-like cognitive symptoms). Arachnoid cysts represent the most common form of benign cyst and occur in the cerebrospinal axis. The size of arachnoid cysts is not directly affected by changes in the ventricular system.