Arachnoid cysts are congenital extra-axial non-neoplastic lesions, filled with CSF ^1,2, which is a common incidental discovery on neuroimaging in all age groups ². The most common location for this entity is the middle cranial fossa ^1,2. The Galassi classification of middle cranial fossa arachnoid cysts uses the size and degree of displacement of the adjacent brain to divide cyst into three types ¹. This case illustrates the typical features of the type II Galassi classification of a left middle cranial fossa arachnoid cyst.

Case courtesy

• Luiz Gonzaga do Nascimento Neto, MD - PGY-2, Radiology Resident, Department of Radiology
• Antonio Rodrigues de Aguiar Neto, MD - Radiologist, Department of Radiology
• Hospital da Restauração – Recife, PE – Brazil