Introduction
Background
Choroid plexus papilloma is a rare, slow-growing, histologically benign intracranial neoplasm that is commonly located in the ventricular system.
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Axial T2-weighted magnetic resonance image (repetition time, 2883 ms; echo time, 100 ms) shows a lobulated mass with frondlike papillary projections in the left lateral ventricle. The mass is isointense relative to the cortex and has internal hypointense foci that likely represent prominent vessels. Note the associated hydrocephalus and transependymal cerebrospinal fluid flow.
Interventricular extension through the foramen of Munro, cerebral aqueduct, or foramen of Luschka or Magendie can occur with a choroid plexus papilloma; this is an ancillary diagnostic sign that is not described with other interventricular tumors.
Pathophysiology
On gross pathologic examination, choroid plexus papillomas appear as lobulated, encapsulated masses. They are neuroectodermal in origin and similar in structure to a normal choroid plexus. Choroid plexus papillomas arise from epithelial cells of the choroid plexus arranged as a multitude of papillary fronds resting on a delicate stroma of fibrovascular connective tissue. Choroid plexus papillomas are often associated with a vascular stalk connected to the choroid plexus, allowing mobility within the ventricular system.
Blood breakdown products and high protein secretion result in hydrocephalus because of obstruction of cerebrospinal fluid (CSF) absorption at the level of the arachnoid granulations. CSF is produced at 4-5 times the normal rate, with resultant communicating hydrocephalus. Hydrocephalus may also result from direct tumor obstruction of the outlet of CSF flow from the ventricular system; this finding is especially true for tumors in the third ventricle, with resultant CSF outflow obstruction at the foramina of Monro.
Bone formation and neuromelanin production may occur, but these are extremely rare. Doran et al described only 6 cases of bone formation,1 and Reimund et al described only 2 cases of neuromelanin production.2
Choroid plexus papillomas are not malignant; however, malignant evolution may occur, with an incidence of 10-30%. The lateral ventricles are the most common sites for malignant degeneration. With a clinical and histologic pattern of malignancy, which is characterized by invasion, mitotic figures, nuclear pleomorphism, necrosis, and metastasis, these tumors are classified as carcinomas.3,4,5
Frequency
International
Papillomas of the choroid plexus are rare, accounting for 0.4-0.6% of all intracranial neoplasms. In children, choroid plexus papillomas account for 1.5-6.4% of intracranial neoplasms.
Mortality/Morbidity
The disease burden of choroid plexus papillomas can be significant, especially in young children. Morbidity is associated with developmental delay in 39% of pediatric patients, severe behavioral problems in 17%, and epilepsy in 48%.
In a series by McEvoy et al, the 5-year survival rate was 100%.6 In a review by McGirr et al, tumors did not recur in half of the patients who underwent subtotal resection.7 Radiation therapy after surgical intervention usually is reserved for the treatment of choroid plexus carcinoma.
If the tumor evolves into malignancy, the prognosis is dismal, with a 5-year survival rate of 26%. However, the histologic appearance may not be predictive of biologic behavior, because some highly anaplastic choroid plexus tumors can be clinically benign, whereas some histologically inactive tumors are invasive.
The presence of mitotic figures, although rare in choroid plexus papillomas, may be predictive of the likelihood of both recurrence and malignant evolution. Such histologic findings in the surgical specimen should result in close clinical follow-up care of patients, especially in those whose postoperative images show findings of residual tumor.
The question of whether chemotherapy improves the prognosis has been raised. A meta-analysis of individual cases with choroid plexus tumors was performed by Wrede et al and demonstrated the subset of choroid plexus carcinoma (CPC) patients who received chemotherapy had a statistically better survival than those who did not receive chemotherapy.8 The benefit of chemotherapy was also significant when the analysis was restricted to the subgroup of patients with less than completely resected CPC (2-year overall survival [OS] 54.8 +/– 7% (standard deviation [SD] vs 24.4 +/– 7%, P < 0.0001). The authors' conclusion was that patients with less than completely resected CPC should receive chemotherapy.
Race
No racial predilection is reported in choroid plexus papilloma.
Sex
The male-to-female ratio of choroid plexus papilloma is 2.8:1, as Sarkar et al reported in a review of 23 cases.9
Age
Most choroid plexus papillomas appear as large tumors in young individuals. They are more common in children than in adults, with a mean patient age of 5.2 years. Of all choroid plexus papillomas, 20% occur in patients younger than 1 year old, and 85% occur in those younger than 10 years old. Choroid plexus papillomas may be discovered at birth. They account for approximately 40% of pediatric tumors that are present within the patient's first 60 days of life.
Anatomy
Choroid plexus papillomas may arise wherever a choroid plexus exists. In all age groups, the sites at which choroid plexus papillomas occur, in order of frequency, are the lateral ventricles (43%), fourth ventricle (39%), third ventricle (10%), and cerebellopontine angle (8%).
Tumoral distribution varies between pediatric and adult patients. In children, most choroid plexus papillomas (80%) are located in the lateral ventricles. McEvoy et al described no predilection for the left or right side,6 whereas other authors, such as Hopper et al,10 report an increased incidence of tumors in the left lateral ventricle. About 16% of papillomas are found in the fourth ventricle, and 4% are found in the third ventricle. In those aged 0-10 years, the relative incidence of third ventricular papillomas approaches 30%. The fourth ventricle is the most common location of choroid plexus papillomas in adults.
Choroid plexus papillomas can occasionally be bilateral or multiple. Interventricular extension can occur with a choroid plexus papilloma; this sign is not described with other interventricular tumors. Although uncommon, interventricular extension through the foramen of Munro, cerebral aqueduct, or foramen of Luschka or Magendie is a helpful diagnostic sign (see Image below and Image 5 in Multimedia).
Interventricular extension through the foramen of Munro, cerebral aqueduct, or foramen of Luschka or Magendie can occur with a choroid plexus papilloma; this is an ancillary diagnostic sign that is not described with other interventricular tumors.
Choroid plexus papillomas can arise in the cerebellopontine angle secondary to direct extension from tufts of choroid protruding through the foramen of Luschka. Extension into the foramen magnum may occur, with possible brainstem compression. Seeding can occur throughout the cerebrospinal axis; this usually results in a solitary metastasis from a lateral ventricular tumor in a child and in subarachnoid seeding to the spine from a fourth ventricular lesion in an adult. On rare occasions, widespread metastases from benign papillomas are observed.
A few dozen cases of papillomas of a nonventricular origin are reported. These are possibly explained by an origin in the embryonic rests of choroid plexus.
Extraventricular spread to the brain parenchyma, pineal region, or suprasellar area, as well as drop metastasis, is observed on occasion. Bone invasion may rarely occur; most commonly, this involves the petrous bone. Usually, involvement of bony structures implies the presence of CPC or malignant transformation of a benign papilloma. Carpenter et al described a single case report of extension to the cavernous sinus and invagination into the jugular foramen.11
Presentation
Signs and symptoms
In a review of 25 cases by McEvoy et al, the median duration of choroid plexus papilloma symptoms was 1 month, and approximately one third of patients presented within 2 weeks.6
The tumor's presence is often heralded by nonspecific signs and symptoms of increased intracranial pressure, which is present in 91% of patients, frequently in association with obstructive hydrocephalus. Vomiting is the most common sign in children. The presentation can also include hemiparesis, homonymous visual field defects, and generalized tonic/clonic and focal seizures.
When the neoplasm arises within the cerebellopontine angle, the presentation usually involves ataxia and cranial nerve palsy, most commonly that of cranial nerves V, VII, or VIII. In adults, headache is the most common presenting symptom; this finding may be related to an alteration in head position.
Gradin et al reported a case of sudden death in which the tumor involved the third ventricle, causing acute ventricular obstruction.12
Consider choroid plexus papilloma when an expansile, calcified, and vascular mass is closely associated with the ventricular system or cerebellopontine angle, especially in the presence of nonobstructive hydrocephalus.
Surgical treatment
As a result of their benign nature and slow growth, choroid plexus papillomas are amenable to complete surgical excision, with an expectation of total cure. Not surprisingly, a favorable long-term outcome is expected; the goals are a cure for all children and no requirement for adjuvant therapy. These goals are especially achievable if surgery can be performed early, before hydrocephalus or spontaneous hemorrhage cause irreversible damage.13
Despite advances in modern surgical techniques, such as the use of surgical microscopes, bipolar coagulation, stereotaxy, and image-guidance techniques, a significant risk of mortality and morbidity may be associated with surgical treatment.
Malignant progression of choroid plexus papillomas has been occasionally reported. Frequency and extent of malignant progression were examined in a retrospective series of 124 primary choroid plexus papillomas by Jeibmann et al.14 The authors described recurrent tumor growth after gross-total resection in a small minority of their study group (6% of choroid plexus papillomas [World Health Organization (WHO) Grade I]) and 29% of atypical choroid plexus papillomas [WHO Grade II]).14 Malignant progression to choroid plexus carcinoma did occur in a small percentage of tumors (2 of 124 cases followed for a total period of 59 mo).14
Although the details are beyond the scope of this article, extreme tumor vascularity, which is often present, may hinder complete resection. The perioperative management of hydrocephalus, which is common in patients with choroid plexus papillomas, is controversial; especially controversial is the timing or necessity for shunt creation. Subdural fluid collections, frequently caused by the persistence of a ventriculosubdural fistula, are often found in the postoperative period; occasionally, these can cause symptoms of increased intracranial pressure.
Preferred Examination
Computed tomography (CT) scanning and magnetic resonance imaging (MRI) are the investigative procedures of choice in the evaluation of choroid plexus papillomas. Because of the relatively noninvasive nature, ease, widespread availability, high reproducibility, and great contrast resolution of CT scanning and MRI, these examinations have supplanted all other methods of neuroimaging.
With the addition of intravenously administered contrast material, the sensitivity of these imaging modalities approaches 100%. The multiplanar capability of MRI further aids in the characterization and localization of lesions.
Differential Diagnoses
Astrocytoma, Brain
Brain, Metastases
Ependymoma, Brain
Epidermoid, Brain
Hemangioblastoma, Brain
Other Problems to Be Considered
Acoustic neuroma (if tumor is in cerebellopontine angle)
Choroid plexus carcinoma
Choroid plexus cysts
Choroid plexus lipoma
Epidermoid
Glioma
Hematoma
Meningioma
Metastasis, choroid
Papillary ependymoma (in children and in the presence of larger extraventricular components and fourth ventricular origin)
Pilocytic astrocytoma and hemangioblastoma (when tumor presents as cyst with mural nodule)
Sarcoma
Xanthogranuloma
More on Choroid Plexus Papilloma |
 Overview: Choroid Plexus Papilloma |
| Imaging: Choroid Plexus Papilloma |
| Follow-up: Choroid Plexus Papilloma |
| Multimedia: Choroid Plexus Papilloma |
| References |
| Further Reading |
| Next Page » |
References
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Further Reading
Management of brain metastases: role of radiotherapy alone or in combination with other treatment modalities.
Program in Evidence-based Care. 2004 Mar 30. 35 pages. NGC:003529
Pre-irradiation evaluation and management of brain metastases.
American College of Radiology. 1999 (revised 2005). 7 pages. NGC:004635
Keywords
choroid plexus papilloma, CPP, choroid plexus neoplasm, choroid plexus tumor, benign intracranial neoplasm, cerebral ventricle neoplasm, brain neoplasm, brain tumor
