Fourth ventricle lesion: Answer

Abstract

Choroid plexus cyst. The patient underwent a suboccipital craniotomy and removal of the dorsal arch of C1 in the prone position. The cyst, which was presenting at the foramen of Magendie, was opened and deflated. The wall was separated from the surrounding structures with blunt dissection and completely removed. There was some vascular attachment to the choroid plexus on the roof of the fourth ventricle that was transected to separate the cyst and remove it. The macroscopic appearance of the cyst was smooth, mobile and tan-pink in colour. Histopathological analysis of the cyst is shown in Fig. 2. The choroidal origin of the epithelium was confirmed by showing focal immunohistochemical positivity for transthyretin and cytokeratin AE1/AE3, and no immunoreactivity to S100 or glial fibrillary acidic protein (GFAP). The pathological diagnosis of the lesion was benign Choroid Plexus Cyst (CPC). Choroidal cysts of the ventricular system are usually small-sized asymptomatic lesions that are incidentally encountered at autopsy and their size does not usually extend beyond 15–20 mm in diameter [1Choi J.H. et al.A symptomatic choroid plexus cyst in the lateral ventricle: case report.J Korean Neurosurg Soc. 1998; 27: 1283-1287Google Scholar, 2Netsky M. Shuangshoti S. Origin of choroid plexus and ependyma. The choroid plexus in health and disease. University Press of Virgina, Charlottesville1975: 3-18Google Scholar]. They are most frequently found in children and account for approximately 3% of all paediatric cerebral pathological entities [3Baka J. Sanders W. MRI of hemorrhagic choroid plexus cyst.Neuroradiology. 1993; 35: 428-430Crossref PubMed Scopus (7) Google Scholar, 4Odake G. Tenjin H. Murakami N. Cyst of the choroid plexus in the lateral ventricle: case report and review of the literature.Neurosurgery. 1990; 27: 470-476Crossref PubMed Scopus (33) Google Scholar]. They may be single or multiple and generally located around the trigone of the lateral ventricles [[5]Giorgi C. Symptomatic cyst of the choroid plexus of the lateral ventricle.Neurosurgery. 1979; 5: 53-56Crossref PubMed Scopus (13) Google Scholar]. These congenital cysts are thought to arise from entanglement of villi from the rapidly growing choroid plexus that traps CSF and cellular debris to take on the appearance of a cyst [[6]Kennedy KA, Carey JC. Choroid plexus cysts: significance and current management practices. In: Seminars in ultrasound, CT and MRI, Elsevier: 1993.Google Scholar]. They are commonly found during the second trimester of normal fetuses, and appear to be more common in aneuploidy, particularly trisomy 18 [[7]McLennan M. Radiology rounds choroid plexus cysts.Can Fam Phys. 1997; 43: 1357PubMed Google Scholar]. The occurrence of symptomatic CPCs within the fourth ventricle are evidently extremely rare, more so in adults as most of the foetal cysts regress [[8]New P. Davis K. Intraventricular noncolloid neuroepithelial cysts.Am J Neuroradiol. 1981; 2: 569-576PubMed Google Scholar]. On CT imaging, cystic lesions usually appear as a well-defined mass of similar low density to CSF. MR brain imaging demonstrates the precise location of the cyst within the ventricular system, along with its thin wall often closely applied to the ventricular lining. The cystic contents have a signal on both T1- and T2- weighted MR images, corresponding to CSF [[9]Czervionke L. et al.Neuroepithelial cysts of the lateral ventricles: MR appearance.Am J Neuroradiol. 1987; 8: 609-613PubMed Google Scholar]. The differential diagnoses include ependymal cyst, parasitic cysts as found in neurocysticercosis and hydatidosis, and epidermoid cysts. Ependymal cysts tend to be intracerebral with a tendency to displace rather than expand the ventricle and show immunopositivity to GFAP [[3]Baka J. Sanders W. MRI of hemorrhagic choroid plexus cyst.Neuroradiology. 1993; 35: 428-430Crossref PubMed Scopus (7) Google Scholar]. The parasitic cysts are commonly accompanied by surrounding cysts, with or without peripheral enhancement and calcification, and may contain a mural nodule representing the scolex [[8]New P. Davis K. Intraventricular noncolloid neuroepithelial cysts.Am J Neuroradiol. 1981; 2: 569-576PubMed Google Scholar]. Epidermoid cysts can potentially mimic a choroid plexus cyst because they occur largely within the fourth ventricle and their contents have the same density as CSF. However, their MRI appearance varies depending on the lipid and keratin content [3Baka J. Sanders W. MRI of hemorrhagic choroid plexus cyst.Neuroradiology. 1993; 35: 428-430Crossref PubMed Scopus (7) Google Scholar, 10Martínez-Lage J.F. et al.Congenital arachnoid cyst of the lateral ventricles in children.Child's Nervous Syst. 1992; 8: 203-206Crossref Scopus (42) Google Scholar]. The patient recovered uneventfully with improvement of his gait. Postoperative MR scan showed no residual cyst and CT brain scan 4 weeks postoperatively showed no hydrocephalus. Fourth ventricle lesion: QuestionJournal of Clinical NeuroscienceVol. 45PreviewA 61 year-old man presented with a one-year history of progressive gait disturbance, dizziness, episodes of blurred vision and mild headache. There was no associated ataxia, focal neurological deficits or papilloedema. He had a history of hypertension, which was well controlled. Full-Text PDF