Specific Imaging Findings Choroid plexus papilloma (CPP) is seen on imaging studies as a large, intraventricular cauliflower-like mass that may adhere to the ventricular wall but is usually separated from brain tissue. The tumor is typically T1 iso- to hypointense and iso- to hyperintense to gray matter on T2WI. Diffusion is slightly increased with respect to the brain parenchyma. Presence of calcifications and/or hemorrhages may locally modify the signal of the tumor and may also be seen on CT scans. CT otherwise shows an iso- to hypodense mass consistent with low tumor cellularity. Intense and homogeneous contrast enhancement is due to rich vascularity. Enlarged feeding arteries may be identified on both MRI and MR angiography. In supratentorial CPP, the blood supply is provided by the anterior, posterolateral and posteromedial choroidal arteries, whose tumoral branches are constantly hypertrophied, tortuous, and elongated. Albeit rarely, benign CPP may spread cells into the CSF; thus, contrast-enhanced MRI of the entire neuraxis is warranted for correct disease staging. Pertinent Clinical Information Raised intracranial pressure secondary to hydrocephalus is the most frequent presentation of children with CPP regardless of location. The hydrocephalus is caused by either CSF overproduction by the tumor, obstruction of CSF flow, or both. Newborns or small infants may present with macrocrania and a progressive increase of head circumference prior to developing neurological signs.
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