Low power of partially encapsulated tumor 1.5 cm with a papillary interior structure
At higher power some cells appear to be ciliated and secretory
Papillary pattern differs from normal choroid plexus
Concentrated on surface, cytosolic uptake tight junctions, unusual for neuronal cells
Harbor UCLA Neuro-Radiology Case #9
HARBOR UCLA NEURO CASE # 9Marcia Cornford, MD, PhD, Department of Pathology Anton Mlikotic, MD, Department of RadiologyLos Angeles CountyDepartment of Health Sciences
Clinical presentationThe patient is a 37 year old woman referred from anoutside hospital for workup of an intracranial mass.
T1 and contrast-enhanced T1 weighted images centered on the posterior fossa reveal a complexmass in the region of the cerebellopontine angle cistern. There is an enhancing solid component andsuggestion of a discrete cystic component. There is mass effect on the brain stem which is partiallyeffaced and displaced to the left, although there was no hydrocephalus.
This FLAIR image shows associated edema and / or gliosis in the neighboring brachium pontisand superior cerebellum.
The FIESTA sequence demonstrates the relationship of the mass to the subarachnoid space andprovides better anatomic detail of its structure. This image shows the solid component (S), whichis isointense to the brain signal, and both a macrocystic (A) and microcystic component (B).
A cluster of microcysts rests against lateral wall of the fourth ventricle (4), causing inward bowingof the wall and stretching of the ventricle. Note visualization of the facial and vestibular nerves inthe porus acousticus of the internal auditory canal (arrow).
Note the normal caliber of the foramen of Lushka on the left (arrow). On the right, it is occupiedby the mass which extends into the cerebellopontine angle cistern.
Digital subtraction diagnostic cerebral angiographyDigital subtraction angiography reveals subtle enhancement of the solid component of the mass,supplied by tiny choroidal branches arising from the posterior inferior cerebellar artery.
Differential DiagnosisBased on location, which of the following entities should be considered ? Arachnoid cyst Endolymphatic sac tumor Dermoid cyst Pituitary adenoma Epidermoid cyst Trigeminal nerve schwannoma Neurenteric cyst Vestibular nerve schwannoma Neuroepithelial cyst Hypoglossal nerve schwannoma Aneurysm Brain stem glioma Metastasis Lymphoma Cholesterol granuloma Ependymoma Paraganglioma Choroid plexus papilloma Petrous apicitis Hemangioblastoma Chordoma Medulloblastoma Chondroma Dysembryoplastic neuroepithelial Lipoma tumor
Differential DiagnosisA mass in the cerebellopontine angle cistern may include all of these entities, althoughmany only rarely present in this location: Arachnoid cyst Endolymphatic sac tumor Dermoid cyst Pituitary adenoma Epidermoid cyst Trigeminal nerve schwannoma Neurenteric cyst Vestibular nerve schwannoma Neuroepithelial cyst Hypoglossal nerve schwannoma Aneurysm Brain stem glioma Metastasis Lymphoma Cholesterol granuloma Ependymoma Paraganglioma Choroid plexus papilloma Petrous apicitis Hemangioblastoma Chordoma Medulloblastoma Chondroma Dysembryoplastic neuroepithelial Lipoma tumor
At low power, the surgical specimen stained with hematoxalin and eosin shows a partially encapsulatedtumor with an internal papillary architecture and highly vascularized fibrous stroma.
At higher power, some cells appear to be ciliated and secretory, and there are collections ofproteinaceous material forming cystic spaces.
The papillary pattern differs from that of normal choroid plexus.
Immunohistochemical staining with synaptophysin shows uptake within the cytosol, withconcentration along the surface. No synaptic connections are identified.
On histochemical staining, the papillary pattern of the tumor is different from thatexpected for normal choroid plexus. This pattern may be appreciated with certainpapillary neoplasms, including thyroid cancer and endolymphatic sac tumors. However,immunohistochemical positivity for synaptophysin favors a tumor of choroid plexuslineage. The mass is strongly positive for cytokeratin and vimentin. The frond-likearchitecture with highly vascularized fibrous stroma is typical for choroid plexuspapilloma.In contradistinction, choroid plexus carcinomas show a brisk proliferation index onMIB-1 (Ki-67) immunohistochemical staining and the majority show nuclear positivityfor p53. In addition, INI-1 reactivity is also maintained, which would distinguish thismalignant subtype from atypical rhabdoid-teratoid tumor.
Immunohistochemical profile for choroid plexus papilloma MARKER CYTOKERATIN ++ VIMENTIN ++ SYNAPTOPHYSIN + S 100 + GFAP + TRANSTHYRETIN + Information derived from the Manual of Basic Neuropathology, 4th Edition
Choroid plexus papillomaThe choroid plexus consists of neuroepithelial tissue that is responsible forcerebrospinal fluid production within the ventricular system. Most of thistissue is concentrated in the region of the atrium, although it does extendanteriorly towards the foramen of Monro and is present in the third andfourth ventricle, where it exits the foramen of Lushka.The lateral ventricle is the most common site for neoplasms arising fromchoroid plexus tissue (50% of cases), followed by the fourth ventricle (40%).Approximately 5% of choroid plexus tumors are multicentric. Extra-ventricular locations have also been reported, including the cerebellopontineangle cistern, suprasellar region, pineal space, posterior commissure, andwithin the supratentorial and intratentorial brain matter. It is purportedthat an embryonic rest of choroid plexus tissue may account for these extraventricular lesions.
Choroid plexus papillomaChoroid plexus neoplasms account for 0.4to 0.6% of all intracranial tumors, half ofwhich occur in the first decade of life. Nearly 80% occur as a benign, slowly growingpapilloma although as many as 20% are more aggressive most of which present inchildhood.The age of presentation varies with location. Those seated in the lateral ventricle aremuch more common in patients under the age of ten whereas those arising in the fourthventricle are much more common in the older population.
Choroid plexus papillomaChoroid plexus tumors are associated with hydrocephalus and symptoms relate toincreased intracranial pressure, secondary to an increased production of cerebrospinalfluid by the tumor, far exceeding the average of 450 ml per day normally produced. Inaddition, persistent hydrocephalus requiring post-operative shunting directs to aproblem in CSF absorption at the level of the arachnoid granulations.In addition to headache, clinical findings may include focal neurologic deficits, cranialnerve palsies, seizures, and coma. There have also been associations with Li-Fraumeniand Aicardi syndrome.
Choroid plexus papillomaMacroscopically choroid plexus papillomas are described as soft, cauliflower like masseswith prominent peripheral lobulations. Hemorrhage and cyst formation may be seen,and necrosis and parenchymal invasion findings associated with more aggressive(malignant) varieties . Many are attached via a vascular pedicle to the choroid plexus inthe lateral ventricle in the region of the trigone.Prominent fronds of fibrovascular connective tissue surrounded by columnar orcuboidal cells without significant mitotic activity are characteristic features.Choroid plexus carcinoma demonstrates clear signs of malignancy with hypercellularity,nuclear pleomorphism, a high nucleus-cytoplasmic ratio, brain invasion, and highmitotic activity.
Choroid plexus papillomaSurgical resection of these highly vascular tumors has been facilitated by improvedtechniques to secure the vascular supply and pre-operative embolization. The prognosisfor patients with choroid plexus papilloma today continues to be excellent, with 100%survival at 5 years. Unfortunately, the patient prognosis for patients with choroid plexus carcinomaremains guarded, with a 5 year survival of only 26-50%. Adjuvant radiation therapy isoften prohibited in younger populations and chemotherapy has yet known provenefficacy.
Imaging CharacteristicsOn unenhanced CT imaging, the mass shows hyperattenuation, with possible cysticcomponents and calcifications and, in some cases, erosion of the petrous bone.On MRI, the mass is isointense to hypointense with respect to the brain parenchyma,and shows homogeneous enhancement of the solid component following gadoliniumadministration. Internal flow voids are commonly appreciated, with minimal, if anyedema in the adjacent brain stem.As the lesion may cause subarachnoid seeding, complete imaging of the neuroaxisis recommended.Angiography reveals blood supply arising from the anterior and posterior choroidalartery, when located in the lateral ventricle, and by choroidal branches of theposterior inferior cerebellar artery when located in the fourth ventricle or foramen ofLushka.
World Health Organization (WHO) Classification Choroid Plexus Papilloma WHO Grade I Atypical Choroid Plexus Papilloma WHO Grade II Choroid Plexus Carcinoma WHO Grade III
Operative course and follow-upA suboccipital craniotomy was performed to remove the mass,with successful debulking of 95% of the tumor burden. Follow-upimaging at four months showed expected post-operative findingsalthough there was no evidence for a residual or recurrent mass.
Which neurocutaneous syndrome is suggested by the presence ofbilateral cerebellopontine angle masses?
According to recent World Health Organization (WHO) criteria, thepresence of bilateral CPA masses suggests Neurofibromatosis Type 2,a tumor suppressor gene disorder localized on the long arm ofChromosome 22.