Hemorrhage into an intradiploic arachnoid cyst

Abstract

Intracranial arachnoid cysts are relatively rare; it is believed that they account for only 1% of all intracranial space-occupying lesions. When they occur in the intracranial cavity, they usually develop in relation to an arachnoid cistern as a pocket of cerebrospinal fluid within two layers of arachnoid membrane. Five cases of intradiploic arachnoid cysts have been reported, but an arachnoid cyst presenting as an extradural mass has not been described before. The authors present an unusual case of hemorrhage into a massive intracranial extradural arachnoid cyst with no intradural communication.

Intradiploic Arachnoid Cyst Presenting as a Frontal Sinus Mass

“…The cause of the arachnoid cyst remains unclear. Suggested mechanisms include primary cerebral agenesis, subarachnoid hemorrhage, congenital sequestration, trauma, and inflammation 2,3,6,7,9,10,14,15 . A developmental pathogenesis is supported by histologic and ultrastructural studies of the cyst wall, and the most consistent finding is a split and duplicated arachnoid membrane 4,13–15 .…”

“…Since the original description of an arachnoid cyst by Bright in 1831, 1 various terms have been used to describe this entity, including external hydrocephalus, cerebral pseudotumor, subdural hygroma, chronic cystic arachnoiditis, leptomeningeal cyst, and meningitis serosa circumscripta. Arachnoid cysts are rare lesions of the cerebrospinal axis, accounting for only 1% of all intracranial space‐occupying lesions 2 , 3 . Most occur in the middle cranial fossa, but they may develop at any site in which arachnoid membrane is located, and multiple cysts may be present 4 , 5 .…”

“…Most occur in the middle cranial fossa, but they may develop at any site in which arachnoid membrane is located, and multiple cysts may be present 4 , 5 . Extradural cysts appear to be extremely uncommon, and a review of the literature revealed only 11 previously reported intradiploic arachnoid cysts, 2 of which involved the frontal bone 3,5–8 …”

Intradiploic Arachnoid Cyst Identified by Diffusion-Weighted Magnetic Resonance Imaging. Case Report.

“…Some IACs were associated with former skull fracture. 7,11,13) In most cases, including ours, the patient had no history of head injury. 1,3,4,8,10,15) The 12 previous and the present patients with IAC without antecedent head injury had a mean age of 61.6 years, and all except one 10) were over 50 years ( Table 1).…”

Intraosseous arachnoid cyst of the skull. Clinical case

“…В ряде Существует нетравматическая теория возникновения внутрикостной арахноидальной кисты, согласно которой инвагинация арахноидальной оболочки внутрь кости происходит через врожденные дефекты ТМО и внутренней кортикальной пластинки [15]. A. Hande и P. Karapurkar считают, что внутрикостные арахноидальные кисты представляют собой гипертрофированные пахионовы грануляции [16].…”