[Arachnoid cyst complicated by intracystic hemorrhage and spontaneous subdural hematoma: magnetic resonance findings].

Arachnoid cysts are collections of cerebrospinal fluid within the arachnoid membrane. They are benign lesions and most are congenital. They are usually asymptomatic; however, they can bleed and become symptomatic. Although arachnoid cyst associated to intracystic hemorrhage and spontaneous subdural hematoma is an uncommon complication, it is a well-known indication for emergency neurosurgery. We present the findings in a ten-year-old boy diagnosed with arachnoid cyst complicated by intracystic hemorrhage and spontaneous subdural hematoma diagnosed by magnetic resonance.