Choroid plexus papilloma
Synonyms and keywords: Choroid plexus papillomas; Papilloma of choroid plexus; Papilloma of the choroid plexus; CPP

# Overview
Choroid plexus papilloma is a a rare, slow-growing, histologically benign intracranial tumor that is commonly located in the ventricular system of the choroid plexus. It may obstruct the cerebrospinal fluid flow, causing elevated intracranial pressure. Choroid plexus papilloma is neuroectodermal in origin and similar in structure to a normal choroid plexus. They may be created by epithelial cells of the choroid plexus. Choroid plexus papilloma may be associated with Aicardi syndrome, Von Hippel-Lindau disease, and Li-Fraumeni syndrome. On gross pathology, choroid plexus papilloma is characterized by a soft, solid, pink to red, capsulated, vascular, and friable cauliflower-like mass. On microscopic histopathological analysis, choroid plexus papilloma is characterized by papillary structures with a delicate fibrovascular core lined by columnar or cuboidal epithelial cells with vesicular nuclei. Its appearance is very similar to normal choroid plexus. Choroid plexus papilloma is demonstrated by positivity to tumor marker such as cytokeratin (CK7). Choroid plexus papilloma may be differentiated from choroid plexus carcinoma, choroid plexus metastasis, medulloblastoma, and intraventricular meningioma. Choroid plexus papilloma accounts for approximately 1% of all brain tumors, 2-6% of all pediatric brain tumors, and 0.5% of the adult brain tumors. Choroid plexus papilloma is a rare disease that tends to affect children and adults. Males are more commonly affected with choroid plexus papilloma than females. The male to female ratio is approximately 2.8 to 1. If left untreated, patients with choroid plexus papilloma may progress to develop seizures, hydrocephalus, focal neurological deficits, cranioneuropathies, psychosis, and coma. Common complications of choroid plexus papilloma include CSF seeding, obstructive hydrocephalus, blindness, psychosis, and coma. The prognosis is excellent, and the 5-year survival rate after complete excision of choroid plexus papilloma is approximately 100%. Symptoms of choroid plexus papilloma include headache, vomiting, seizures, and vision loss. Common physical examination findings of choroid plexus papilloma include bulging fontanelle, enlarged head size, papilledema, altered mental status, and cranioneuropathies (6th and 7th nerve palsy). Head CT scan and brain MRI are helpful in the diagnosis of choroid plexus papilloma. On CT scan, choroid plexus papilloma is characterized by iso- to hyperdense well-defined lobulated masses with intense homogenous enhancement and associated hydrocephalus. If there is markedly heterogeneous contrast enhancement, a choroid plexus carcinoma should be suspected. On MRI, choroid plexus papilloma is characterized by a well demarcated, extra-axial mass that is iso- to hypointense on T1-weighted imaging and iso- to hyperintense on T2-weighted imaging. On contrast administration, there is generally marked homogenous enhancement. The predominant therapy for choroid plexus papilloma is surgical resection. Radiotherapy is indicated for the inoperable residual tumor or resistant/aggressive subtype, whereas chemotherapy is reserved for the recurrent tumors.

# Historical Perspective
Choroid plexus papilloma was first described by Guerard, in 1832.

# Classification
Choroid plexus papilloma may be classified into two groups:

# Pathophysiology
- Choroid plexus papilloma is neuroectodermal in origin and similar in structure to a normal choroid plexus. They may be created by epithelial cells of the choroid plexus.
- It may be a true congenital intracranial neoplasm.
- Choroid plexus papilloma may be associated with:
- Aicardi syndrome
- Von Hippel-Lindau disease
- Li-Fraumeni syndrome
- On gross pathology, choroid plexus papilloma is characterized by a soft, solid, pink to red, capsulated, vascular, and friable cauliflower-like mass.
- Unlike most other brain tumors which are more common in the posterior fossa in children and supratentorial compartment in adults, the relationship is reversed for choroid plexus papillomas:
- Adults: 70% occur in the fourth ventricle
- Children: most often occur in the lateral ventricles, with a predilection for the trigone
- Third ventricular, cerebellopontine angle, parenchymal and even pineal region tumors have also been described.

## Gallery
- Gross pathological specimen of choroid plexus papilloma.

# Microscopic Pathology
- On microscopic histopathological analysis, choroid plexus papilloma is characterized by papillary structures with a delicate fibrovascular core lined by columnar or cuboidal epithelial cells with vesicular nuclei. Its appearance is very similar to normal choroid plexus.
- If two or more mitoses are present per 10 high power field (HPF), then the tumor is designated an atypical choroid plexus papilloma and is classified as a WHO grade II tumor.

## Gallery
- Shown above is a micrograph of choroid plexus papilloma (H&E stain).

# Causes
- There are no established causes for choroid plexus papilloma.

# Differentiating Choroid Plexus Papilloma from other Diseases
Choroid plexus papilloma may be differentiated from:
- Choroid plexus carcinoma
- Choroid plexus metastasis
Among children, choroid plexus papilloma must be differentiated from:
- Medulloblastoma
- Atypical teratoid rhabdoid tumor (AT/RT)
- Papillary anaplastic ependymoma
- Pineocytoma
- Pineoblastoma
Among adults, choroid plexus papilloma must be differentiated from:
- Intraventricular meningioma
- Subependymoma
- Central neurocytoma

# Epidemiology and Demographics

## Prevalence
- Choroid plexus papilloma accounts for approximately 1% of all brain tumors, 2-6% of all pediatric brain tumors, and 0.5% of the adult brain tumors.
- They are far more common than the more aggressive choroid plexus carcinoma (WHO grade III), which they outnumber 5:1.

## Age
- Choroid plexus papilloma is a rare disease that tends to affect children and adults.
- Approximately 85% of all choroid plexus papilloma occurs in children under the age of 5 years.

## Gender
- Males are more commonly affected with choroid plexus papilloma than females. The male to female ratio is approximately 2.8 to 1.

# Risk Factors
- There are no established risk factors for choroid plexus papilloma.

# Screening
- There is insufficient evidence to recommend routine screening for choroid plexus papilloma.

# Natural History, Complications and Prognosis
- If left untreated, patients with choroid plexus papilloma may progress to develop seizures, hydrocephalus, focal neurological deficits, cranioneuropathies, psychosis, and coma.
- Common complications of choroid plexus papilloma include CSF seeding, obstructive hydrocephalus, blindness, psychosis, and coma.
- The prognosis is excellent, and the 5-year survival rate after complete excision of choroid plexus papilloma is approximately 100%.

# Diagnosis

## Symptoms
- When evaluating a patient for choroid plexus papilloma, you should take a detailed history of the presenting symptom (onset, duration, and progression), other associated symptoms, and a thorough family and past medical history review.
- Other specific areas of focus when obtaining the history include the review of common associated conditions such as Aicardi syndrome, Von Hippel-Lindau disease, and Li-Fraumeni syndrome.
- Symptoms of choroid plexus papilloma include headache, vomiting, seizures, and vision loss.

## Physical Examination
Common physical examination findings of choroid plexus papilloma include:

## HEENT
- Bulging fontanelle
- Enlarged head size
- Papilledema
- Homonymous hemianopia
- Mild upward gaze paresis
- Facial asymmetry

## Neurological
- Altered mental status
- Gait ataxia
- Focal neurological deficits
- Cerebellar signs
- Cranioneuropathies
- 6th and 7th nerve palsy

## Laboratory Findings
- There are no specific laboratory findings associated with choroid plexus papilloma.
- Other laboratory findings consistent with the diagnosis of choroid plexus papilloma is immunohistochemistry.

### Immunohistochemistry
- Choroid plexus papilloma is demonstrated by positivity to tumor marker such as cytokeratin (CK7).
- Some reactivity for GFAP and epithelial membrane antigen may be present.

## Imaging Findings

### CT
- Head CT scan is helpful in the diagnosis of choroid plexus papilloma.
- On CT scan, choroid plexus papilloma is characterized by:
- Well-defined lobulated masses
- Iso- or somewhat hyperdense compared to the adjacent brain
- Associated hydrocephalus
- Fine, speckled calcification (25%)
- Microhemorrhage
- Intense homogenous enhancement, with an irregular frond-like pattern
- If there is markedly heterogeneous contrast enhancement, a choroid plexus carcinoma should be suspected

### Gallery
- The mass is relatively well circumscribed, slightly hyperdense compared to grey matter on CT, and following administration of contrast demonstrates vivid enhancement.

## MRI
- Brain MRI is helpful in the diagnosis of choroid plexus papilloma.
- On MRI, choroid plexus papilloma is characterized by:

## Gallery
- Brain MRI T1 with contrast image demonstrates a vividly but heterogeneously enhancing mass in the right side of the 4th ventricle is associated with significant surrounding edema and mass effect. There is ventricular enlargement consistent with non-communicating hydrocephalus.
- Axial T2-weighted MRI image demonstrates a 17 x 16 x 17 mm hyperintense mass within the floor of the fourth ventricle. No extension into the foramen of Luschka is observed.

# Other Imaging Findings
- Other imaging studies for choroid plexus papilloma include magnetic resonance spectroscopy.
- Findings on MR spectroscopy include:
- Elevated choline
- Decreased N-Acetylaspartate (NAA)

# Other Diagnostic Studies
- Other diagnostic studies for choroid plexus papilloma include angiography, which demonstrate intense vascular blush owing to the vascularity of the tumor. Enlarged choroidal arteries may be observed feeding the tumor, with shunting.

# Treatment

## Medical Therapy
The treatment options for choroid plexus papilloma include:

### Radiotherapy
- If complete resection of choroid plexus papilloma is done, then no adjuvant radiotherapy is necessary.
- Indications for radiotherapy include:
- Inoperable residual tumor
- Resistant / aggressive tumor

### Chemotherapy
- Adjuvant chemotherapy is not required if choroid plexus papilloma is completely resected.
- Combination chemotherapy is used in the case of recurrent tumors.

## Surgery
- Surgery is the mainstay of treatment for choroid plexus papilloma.
- Complete resection of the tumor must be attempted in all cases.
- Owing to the highly vascular nature of the tumor, care should be taken prior to and during surgery to prevent any life-threatening bleeding.
- Techniques used to minimize this complication of surgery include:
- Preoperative embolization of small caliber feeding vessels
- Intraoperative usage of tranexamic acid
- Hydrocephalus may be managed either by the placement of an external ventricular drain (EVD),  VP shunt, or endoscopic third ventriculostomy (ETV).
- The approach to the surgery depends on the size, location, and extent of the tumor.
Tumor is in the posterior third ventricle:  infratentorial supracerebellar, transcallosal, occipital transtentorial, or transcortical-transforaminal approaches may be used for resection.
Tumor is in the fourth ventricle: midline suboccipital approach is preferred.
Tumor is in the cerebellopontine angle: midline cerebellomedullary fissure or the conventional retrosigmoid approach may be utilized.
- Tumor is in the posterior third ventricle:  infratentorial supracerebellar, transcallosal, occipital transtentorial, or transcortical-transforaminal approaches may be used for resection.
- Tumor is in the fourth ventricle: midline suboccipital approach is preferred.
- Tumor is in the cerebellopontine angle: midline cerebellomedullary fissure or the conventional retrosigmoid approach may be utilized.

### Radiosurgery
- If complete resection of choroid plexus papilloma is done, then no adjuvant radiosurgery is necessary.
- Indications for radiotherapy include:
- Inoperable residual tumor
- Resistant / aggressive tumor

## Prevention
- There are no primary or secondary preventive measures available for choroid plexus papilloma.