Spontaneous resolution of an asymptomatic intracranial arachnoid cyst

Arachnoid cysts are commonly considered to be benign, congenial, extraparenchymatous anomalies. Small cyst are common incidental findings in children and adults. The aetiology and natural history of arachnoid cysts are not fully understood. In most cases, the presence of the cysts is detected on CT-scans or MRI performed for other reasons. In the literature, there have been few documented cases of arachnoid cysts with spontaneous regression. We reports the case of a silvian arachnoid cyst, which disappeared spontaneously during the 13-year-follow-up period. We review the cases previously reported and the mechanisms underlying the resolution of the arachnoid cysts are discussed.