arachnoid cyst https://github.com/monarch-initiative/mondo/issues/6752 https://github.com/monarch-initiative/mondo/issues/6876 https://rarediseases.info.nih.gov/diseases/17/arachnoid-cysts https://www.malacards.org/card/arachnoid_cyst UMLS:C0078981 Intracranial or spinal cavities containing a cerebrospinal-like fluid, the wall of which is composed of arachnoidal cells. They are most often developmental or related to trauma. Intracranial arachnoid cysts usually occur adjacent to arachnoidal cistern and may present with hydrocephalus; headache; seizures; and focal neurologic signs. (From Joynt, Clinical Neurology, 1994, Ch44, pp105-115) MONDO:0008813 MEDGEN:86860 Orphanet:2356 NCIT:C3455 arachnoid cysts MedDRA:10049005 MESH:D016080 SCTID:33595009 GARD:0000017 obsolete rare genetic developmental defect during embryogenesis central nervous system malformation