title: Prominent internal occipital protuberance misdiagnosed as fourth ventricular mass.
abstract: A prominent internal occipital protuberance was misdiagnosed as a fourth ventricular mass. The primary error was inattention to head positioning. The case is presented both to call attention to the need for careful topographic overlap and to discuss the interesting but normal variant.
mesh_terms: D002551:Cerebral Ventricle Neoplasms / Q000000981:diagnostic imaging*; D003951:Diagnostic Errors; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging; D007223:Infant; D008297:Male; D009778:Occipital Lobe / Q000000981:diagnostic imaging*; D011187:Posture; D012886:Skull / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed