Case of the Month
Section Editor: Nicholas Stence, MD
Children's Hospital Colorado, Aurora, CO
October 2015
Next Case of the Month coming November 3 . . .
Third Ventricle Choroid Plexus Papilloma
- Background:
- Choroid plexus papillomas (CPP) are rare, benign (WHO grade 1) neuroepithelial intraventricular neoplasms that occur in both pediatric and adult populations. They are especially rare in the third ventricle.
- Choroid plexus tumors account for less than 1% of all intracranial neoplasms and 2–4% of brain tumors in children, most commonly occurring in the first year of life. In pediatric populations, 80% arise in the lateral ventricle (atrium), 16% in the fourth ventricle, and 4–5% in the third ventricle.
- CPPs are far more common than the aggressive choroid plexus carcinomas.
- Clinical Presentation:
- Presenting symptoms of choroid plexus tumors are typically related to elevated intracranial pressure and hydrocephalus, either from obstruction of CSF flow or CSF overproduction. Signs and symptoms include enlarging head circumference, bulging fontanelle, headache, vomiting, irritability, papilledema, ataxia, and seizure.
- Key Diagnostic Features:
- Typical CT findings are an isodense or hyperdense lobular tumor with postcontrast enhancement. Hydrocephalus is common. Calcifications have been reported to occur in 25–50% of patients.
- CT angiography may show choroidal artery enlargement in lateral ventricle CPPs.
- On MR imaging, CPPs are typically lobular and iso- to hyperintense on T1 and isointense on T2 sequences. T2 may also show vascular flow voids. The tumors typically show avid gadolinium enhancement, with occasional cystic foci and small areas of necrosis. FLAIR may show transependymal interstitial CSF flow due to obstructive hydrocephalus.
- Conventional angiography may show a vascular tumor with prolonged blush and enlarged choroidal artery.
- Differential Diagnosis:
- Compared with the more commonly occurring colloid cyst, choroid plexus papillomas typically show homogeneous enhancement. Colloid cysts will usually not enhance but can rarely have rim enhancement. As in this case, CPPs may have irregular margins, while colloid cysts should have sharp, well-defined margins.
- It is difficult to distinguish choroid plexus papillomas from carcinomas by imaging. Carcinomas can have more heterogeneous enhancement. Invasion of brain parenchyma may also be a clue.
- Subependymal giant cell astrocytomas are enhancing tumors that occur near the foramen of Monro in the setting of tuberous sclerosis complex.
- Treatment:
- Surgical resection is the treatment of choice, with curative rates of 100%. Total resection can be achieved in the majority of cases, and the tumors rarely recur. Early case series reported operative complications and perioperative mortality due to excessive blood loss. Due to the vascular nature of the tumor, preoperative embolization has been attempted. Subdural fluid collections may occur postoperatively.
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