Imaging is fairly sensitive and specific in affording the diagnosis of this tumor.
On imaging choroid plexus papillomas are characterised by vividly enhancing, usually intraventricular, masses. Hydrocephalus is common.
Location
Unlike most other brain tumours, which are more common in the posterior fossa in children and supratentorial compartment in adults, the relationship is reversed for choroid plexus papillomas:
adults: most often (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 tumours have also been described.
CT
The tumours are usually well-defined lobulated masses, either iso- or somewhat hyperdense compared to the adjacent brain. There is associated hydrocephalus. They usually homogeneously enhance, demonstrating with an irregular frond-like pattern, resulting in a cauliflower-like appearance. If there is markedly heterogeneous contrast enhancement, a choroid plexus carcinoma should be suspected 4.
Fine, speckled calcification is seen within the tumour in approximately 25% of cases 4.
MRI
The frond-like morphology of the tumour can usually be seen, especially following contrast administration. Varying degrees of associated hydrocephalus are also present in almost all cases.
T1: typically isointense cf. to adjacent brain; may be somewhat hypointense.
T2 iso to hyperintense
small flow-voids may be seen within the tumour
T1 C+ (Gd): marked enhancement, tends to be homogeneous
MR spectroscopy
decreased NAA
increased Cho 1).