- Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan
Department of Neurosurgery, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan
DOI:10.4103/2152-7806.86228Copyright: © 2011 Imai M. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Imai M, Tominaga J, Matsumae M. Choroid plexus papilloma originating from the cerebrum parenchyma. Surg Neurol Int 18-Oct-2011;2:151
How to cite this URL: Imai M, Tominaga J, Matsumae M. Choroid plexus papilloma originating from the cerebrum parenchyma. Surg Neurol Int 18-Oct-2011;2:151. Available from: http://sni.wpengine.com/surgicalint_articles/choroid-plexus-papilloma-originating-from-the-cerebrum-parenchyma/
Background:Choroid plexus papilloma (CPP) can develop at a primary intraparenchymal location completely unrelated to the ventricular system. Here, we present a case of CPP that was difficult to diagnose preoperatively.
Case Description:Preoperative imaging and operative findings showed that the tumor originated entirely within the cerebrum parenchyma, with no connections between the tumor and the ventricular system. Histopathological examination of the tumor revealed a papillary structure with a single layer of well-differentiated columnar epithelium in the lesion. Furthermore, part of this lesion had infiltrated the cerebral parenchyma. Therefore, the tumor was diagnosed as CPP, and the diagnosis was confirmed by immunohistological examination.
Conclusions:CPP originating as intraparenchymal growths are extremely rare. Origins of extraventricular CCP are discussed in the context of the literature.
Keywords: Choroid plexus papilloma, intraparenchymal origin, magnetic resonance imaging
Choroid plexus papillomas (CPPs) are comparatively rare neuroectodermal tumors that develop from choroid plexus epithelial cells and account for 0.4–0.6% of all primary brain tumors.[
CPP is usually restricted to within the trigone of the lateral ventricle and the fourth ventricle, shows a clear border, and ordinarily displays no intraparenchymal infiltration.[
A 42-year-old man presented with a 13-year history of intractable tonic seizures that were indicative of right parietal lobe brain tumor. Plain computed tomography (CT) of the head revealed a tumor 40 mm in diameter and consisting of calcification and cyst formation located in the right parietal region. Magnetic resonance imaging (MRI) revealed an area of marked signal hypointensity around the solid component on T2 and T2 *-weighted imaging. These findings were thought to represent the calcification seen on CT, or perhaps hemosiderin deposition due to old hemorrhage. The tumor was located adjacent to the lateral ventricle, and the posterior part of the lateral ventricle was slightly enlarged toward the tumor. Normal choroid plexus of the right lateral ventricle was located in the normal position, and continuity of the normal choroid plexus to the tumor was not confirmed [
(a) Plain computed tomography (CT) of the head revealing a 40-mm-diameter tumor with calcification and cyst formation in the right parietal lobe. (b, c) Axial images are shown for magnetic resonance imaging (MRI). T2 and T2*-weighted imaging shows signal hyperintensity. T2 and T2*-weighted imaging reveals an area of marked hypointensity around the solid component, which may represent the calcification seen on CT or hemosiderin deposition due to an old hemorrhage. (d-f) Coronal images are shown for MRI. T1 gadolinium enhancement shows a heterogeneous contrast effect. Note: The normal-appearing choroid plexus was placed within the lateral ventricle and continuity of the normal choroid plexus and the lesion was not confirmed
A right parietal craniotomy was performed using a navigation system and motor-evoked potentials. A yellowish, granulomatous, moderately hard, slightly lobulated avascular tumor was located in the right parietal lobe, with scant hemosiderin deposition identified within the lesion. The margin of the tumor was covered with predominant gliosis. At the deepest part of the tumor, the tumor was firmly adhered to the subependymal layer of the lateral ventricle. During dissection of the adhered area, the ventricular ependyma was penetrated and the body of the lateral ventricle was visualized through the cavity of the removed tumor. The normal-appearing choroid plexus was placed within the posterior part of the lateral ventricle and continuity of the normal choroid plexus and the tumor was not confirmed. The lateral wall on the lateral ventricle showed a normal appearance and continuous coverage with ependymal [
(a) Intraoperative microscopic view. The yellowish, granulomatous, slightly hard tumor was located in the right parietal lobe. (b) The tumor was firmly adhered to the cerebral ventricular wall, and the lateral ventricle was opened during resection of the deepest part of the tumor. Arrow (←) indicates the tumor margin. Asterisk (*) indicates the opening in the lateral ventricle
Pathological examination of the tumor revealed a papillary structure with a single layer of well-differentiated columnar epithelium in the lesion. Part of this lesion growth had infiltrated the cerebral parenchyma. In addition, activated macrophages were prominent around the cerebral parenchyma and were considered to represent a reactive lesion related to an old hemorrhage. Immunohistochemical examination was accomplished with the antibodies detailed in
(a) The tumor tissue consists mainly of a fibrous component with crystal and hemosiderin deposition and macrophages. Densely proliferating cells with ovoid nuclei and resembling choroid plexus epithelium are observed in the peripheral area, showing a papillary architecture. (b) Vimentin was strongly immunoreactive. (c) N-CAM (CD56) exhibited focal immunoreactivity. (d) EMA exhibited focal immunoreactivity. (e) CK7 exhibited focal immunoreactivity. (f) GFAP was strongly immunoreactive. (g) Podoplanin exhibited focal immunoreactivity, contained a few reactive cells, if any. (h) In addition, activated macrophages were prominent around the cerebral parenchyma and were considered to represent a reactive lesion in relation to an old hemorrhage. (i) Papillary architecture was observed, extending further into the cerebral parenchyma (×100 for a–c, h, i; ×200 for d–g)
The patient showed no postoperative neurological deficits, and cranial MRI confirmed complete removal of the tumor. Postoperatively, seizures were well controlled using antiepileptic drugs.
CPP is a comparatively rare neuroectodermal tumor that develops from choroid plexus epithelial cells, accounting for 0.4–0.6% of all primary brain tumors.[
Several reports have described CPP located outside the ventricular system. Cases involving the cerebellopontine angle or foramen magnum reportedly originated from the choroid plexus through the cerebello-medullary fissure. Kimura et al.,[
Histological findings show that CPP has a structure generally characterized by a layer of cast epithelial cells, an inner stroma comprising connective tissue rich in blood vessels, and papillary growth. These findings revealed clear papillary architecture in part of the CPP in the present patient. Vimentin, CK7, GFAP, EMA and podoplanin are expressed by virtually all CPPs.[
As differential diagnoses, histological examination focused on papillary ependymoma and metastatic brain tumor. However, papillary ependymoma exhibits growths with fingerlike projections lined by a single layer of cuboidal tumor cells with smooth contiguous surfaces and with GFAP-positive tumor cell processes; therefore, this diagnosis was ruled out in the present case. In contrast, CPP and metastatic carcinomas form bumpy, hobnail cellular surfaces that do not feature extensive GFAP-positivity. In addition, primary malignant tumor was excluded in the present case.
Another characteristic finding in this patient was the infiltration of the cerebral parenchyma by tumor growth. We observed a clear papillary architecture in part of the CPP in the present patient. Also, focal immunoreactivity of podoplanin might indicate a characteristic of ectopic CPP. CPP usually presents with well-defined, smooth or lobulated margins, related to the choroid plexus in neuroradiological examination. Our imaging studies have shown that a tumor located within the cerebrum parenchyma was unrelated to the choroid plexus, with no uniform enhancement and with unclear margins from the surrounding structures. Dense calcification and cyst were noted on CT. These findings are infrequent in CPP, with patchy calcification in 24% and cyst in 20% of CPPs.[
One factor explaining why CPP was located in the extraventricular system is very difficult to distinguish on the basis of diagnostic imaging findings alone. This is the second case report in the literature of CPP originating in the cerebrum parenchyma.
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