virchow - robin spaces ( vrs ) or the perivascular spaces ( pvs ) are normal interstitial fluid filled cystic structures in the brain . they are about 1 - 2 mm in size , typically lined by pia mater and are common in places where the penetrating arteries and arterioles enter into the substance of the brain . in this article , we report a child with incidentally detected giant tumefactive perivascular space ( gtpvs ) . a 4-year - male was referred to us for further management of cystic lesions which were initially mistaken for cystic neoplasm . he never lost consciousness and did not have neurological symptoms including headaches , vomiting and seizures . he did not travel outside the united states and has no exposure to pets or farm animals . physical examination including neurological system was within the limits . a magnetic resonance imaging ( mri ) showed three clustered cystic areas in subcortical white matter near the atrium of left lateral ventricle . the larger cyst ( ovoid shaped lateral cyst ) was located in the left temporo - parieto - occipital region , measured 34  32  42 mm and was located just lateral to the atrium of the left lateral ventricle [ indicated by number one of them measured 8.1 mm ( spherical shaped medial cyst ) in diameter , and was located medial to the posterior horn of the left lateral ventricle in the occipital region [ indicated by number the other smaller cyst ( ovoid shaped central cyst ) was located in between the two above mentioned cysts [ indicated by number  3 in the figures 1 and 3 ] . this cyst measured 8.3  20  24 mm , and the choroid plexus was noticed in the periphery . the posterior horn and atrium of left lateral ventricle were distorted due to the pressure effect from these cysts . all the three cysts were hypointense in the t1-weighted sequences and hyperintense in the t2-weighted sequences . the intensity signals of the cysts were isointense to the cerebrospinal fluid ( csf ) in all the sequences . there was no enhancement of the cystic wall after the administration of gadolinium [ figures 1b , 2b and 3a ] . there were no restricted diffusion [ figure 3b ] and there were also no areas of calcification . ( a ) axial t1-weighted image of the brain without contrast showing all the three cysts , noted as  1 , 2 and  3 ; ( b ) axial t1-weighted image of the brain with contrast . there is no enhancement of the wall of the cysts after the administration of gadolinium ( a ) sagittal t1-weighted image of the brain without contrast showing the large lateral cyst identified as  1 ; ( b ) sagittal t-1 weighted image of the brain with gadolinium showing no enhancement of the wall of the lateral cyst ( a ) coronal t1-weighted image with gadolinium showing all the three cysts ( noted as  1 ,  2 and  3 ) and no enhancement of the wall of the cysts ; ( b ) axial diffusion weighted image showing the lateral and central cysts without restricted diffusion from the asymptomatic nature and classical radiological appearance , gtpvs was diagnosed . a decision to follow conservatively was made and he was seen a year later . in the interval period , he did not develop any symptoms . a repeat mri was done a year later and showed the same findings without any increase in size or number of the cystic spaces . the patient was also referred to neurosurgery consultation and a conservative long - term follow - up was advised . the pvs or the vrs were initially reported by virchow in 1851 and robin in 1859 . these spaces are normal interstitial fluid filled spaces that accompany the penetrating vessels of the brain . the pvs directly communicate with the subpial space ; but are separated from the cerebrospinal fluid filled subarachnoid space by a single layer of the pia mater . they are round or oval in shape , have smooth margins , are generally less than 2 mm ( some authors considered less than 5 mm as normal ) in diameter and are located along the path of penetrating blood vessels . they do not enhance with contrast administration and the lesions are isointense with the cerebrospinal fluid . small pvs occur in all age groups and the size is generally larger with advancing age . the most common location of the pvs is along the lenticulostriate arteries , just above the anterior perforated substance and adjacent to the anterior commissure . pvs has been commonly noted in many genetic and metabolic conditions such as mucopolysaccharidosis , mannosidosis , lowe syndrome , coffin - lowry syndrome , megalencephaly and ectodermal dysplasia . furthermore , children with developmental delay , epilepsy , attention deficit hyperactive disorder or benign macrocephaly tend to have enlarged pvs . various names such as gtpvs ,  cavernous dilatation  or poirier 's type iiib  expanding lacunae  are given for these enlargements . authors define gtpvs as pvs equal to or greater than 1.5 cm , occurring as either a solitary lesion or in clusters of multiple contiguous cysts . gtpvs are relatively rare in the pediatric population . out of 37 patients with gtpvs reported by salzman et al . the most common site for the gtpvs is along the penetrating vessels of the mesencephalothalamic region . various possibilities such as increased cerebrospinal fluid pulsations , the ex vacuo phenomenon , or an abnormality of arterial wall permeability and the spiral elongation of the penetrating blood vessels , have been cited as contributing factors . in most instances , the giant pvs are incidentally diagnosed when the imaging is done for various other reasons . in one series of 37 patients with gtpvs , the other less common symptoms reported include dizziness , dementia , visual changes , seizure , syncope , stroke , memory problems , poor balance and poor concentration . surgical or neuroendoscopic interventions are not required unless until these cysts have associated complications such as hydrocephalus . in view of its rarity , the most important consideration in the gtpvs is the diagnostic confusion with other conditions . the differential diagnosis includes cystic neoplasms , parasitic cysts , ventricular diverticula , cystic infarction , non - neoplastic neuroepithelial cysts , and deposition disorders such as mucopolysaccharidosis . the prompt recognition of the pathognomonic radiological features of gtpvs prevents unnecessary investigations such as biopsies or surgical resection . the typical location along and at the site of the penetrating blood vessel , the lack of enhancement with gadolinium , and the isointensity with the csf in all sequences are the pathognomonic features of the gtpvs . . there may be an associated mass effect depending on the size and location of the gtpvs . we conclude that physicians need to be aware of the typical imaging characteristics of gtpvs so that unwanted invasive neurosurgical procedures or frequent repeated imaging of the brain can be prevented .
virchow - robin spaces ( vrs ) or the perivascular spaces are small pial lined , cystic structures in the brain and are filled with interstitial fluid . 
 they are normal spaces , identified in all age groups and are common in places where the penetrating vessels enter into the substance of brain . 
 occasionally , these spaces can be enlarged and are termed as giant tumefactive perivascular spaces ( gtpvs ) . when enlarged , these cysts are commonly confused with other lesions such as cystic neoplasms . 
 the pathognomonic imaging appearance helps in the diagnosis of this condition in most instances and invasive management is unwarranted . 
 we report a 4-year - old male with gtpvs . in our patient , 
 gtpvs were diagnosed incidentally on brain imaging ordered for a head trauma and he was managed conservatively . during 1-year follow - up , he remained asymptomatic and the size of the cysts was virtually unchanged .