• Large extra-axial CSF intensity cystic lesions are seen along the right fronto-parieto-temporal convexity and left anterior temporal region (middle cranial fossa).
• They follow CSF intensity on all sequences:
  • Hypointense on T1WI and hyperintense on T2WI.
  • They show suppression on FLAIR sequence.
  • No restricted diffusion.
• Mass effect on underlying neuroparenchyma.

• Epidermoid cyst
  • incomplete suppression on FLAIR
  • restricted diffusion
  • lobulated appearance
• Non-neoplastic cysts like Neurenteric cyst, porencephalic cyst
• Cystic tumors like Pilocytic astrocytoma

• Neurosurgical referral
• Because of the benign nature of MCFACs, treatment is not necessary in most cases.
• However, in large symptomatic cysts, surgical intervention may be considered, such as cyst fenestration or cystoperitoneal shunting.

Middle cranial fossa arachnoid cysts are classified by the Galassi classification:

• Type I: small in size, occupying anterior temporal region (anterior middle cranial fossa) with no mass effect.
• Type II: occupying anterior and middle temporal region with displacement of temporal lobe.
• Type III: large in size with significant mass effect, filling the entire temporal fossa and extending into the fronto-parietal regions.

Other common locations for Arachnoid cysts include:

• suprasellar cistern
• quadrigeminal cistern
• cerebellopontine angle
• posterior fossa
• spinal

Arachnoid cysts may be associated with Aicardi syndrome and Pallister-Hall syndrome.

Cite this article as:

Awal, S. S. (2023). Arachnoid cysts | Radiology Case. Radiology Vibes. Retrieved from https://radiologyvibes.com/case-details/1103

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