Intracranial arachnoid cysts are congenital collections of fluid that develop within the arachnoid membrane because of splitting or duplication of this structure. It corresponds to 1% of all non-traumatic intracranial mass lesions 1 . Arachnoid cysts most frequently occur in the middle cranial fossa, followed by the posterior fossa, convexity, and suprasellar region. Middle cranial fossa cysts are more often associated with subdural hematoma, subdural hygroma, and intracystic hemorrhage. Usually, the patients present with signs and symptoms of intracranial hypertension, mainly headache and vomiting 2 .We report two cases of arachnoid cysts associated with concurrent subdural collections, describing their clinical presentation, radiographic findings and neurosurgical management. CaSeS Case 1A 15-year-old male patient presented with a 3-day history of headache and vomiting. He reported an episode of mild head trauma without loss of consciousness four days before the admission. There was no history of drugs, alcohol abuse or previous neurological illness. The Glasgow coma score was 14 (confused conversation). Pupil reactions were normal and there was no other abnormality in the neurologic examination. Computed tomography (CT) revealed an arachnoid cyst in the left middle cranial fossa ( Fig 1A) and a low-density crescentic collection across the entire left hemispheric convexity, corresponding to a chronic subdural hematoma, with signs of acute hemorrhage (Fig 1B). The patient underwent surgical treatment with evacuation of the subdural hematoma and endoscopic fenestration of the cyst to obtain communication with the chiasmatic cistern. The recovery was uneventful and an eight months follow-up CT showed a residual non-hypertensive cyst. There was no evidence of any subdural collection. Case 2A healthy 5-year-old male patient presented with a six-day history of intense headache and drowsiness. There was no history of head trauma, hematologic disease or use of any medication that could have possibly caused hemorrhage. The physical examination demonstrated a localized left temporal skull bulging. The

Lhermitte-Duclos disease (LDD), or cerebellar dysplastic gangliocytoma, is a rare type of cerebellar tumor, from unknown origin. Patients can be asymptomatic for several years, but there are usually imprecise neurological signs for long periods.

Atypical rhabdoid teratoid tumors (ARTTs) are rare embryonic tumors, usually localized in the posterior fossa and diagnosed in children under 3 years-old. The treatment includes surgical resection, radio and chemotherapy, and the prognostic is unfavorable, with an average median survival of 1 year. We present the case of a 3-year-old patient, with history of headache and vomiting, followed by absence seizures, temporal automatism, syncope accompanied by sialorrhea and sphincteric loss succeeded by a postictal period. Surgical excision was performed and the anatomopathological study confirmed ARTT. The ARTTs are embryonic tumors, a category in which medulloblastoma and primitive neuroectodermal tumors (PNETs) represent the most common central nervous system (CNS) malignancies in childhood.