Radiopaedia.org

FINDINGS: A well-defined rounded nodular lesion measuring about 2.5 x 2.3 cm is sen in the roof of the third ventricle. The lesion is causing obstruction of the foramen of Monro, leading to mild dilatation of both lateral ventricles. The lesion is minimally hyperintense on T1W and mildly hypointense on T2 weighted images and shows mild peripheral ring-like enhancement. A few small mildly enhancing nodules which are hyperintense on T1W and hypointense on T2 are seen along its superior margin. The internal cerebral veins are seen stretched over the lesion. No obvious aneurysm is noted in the circle of Willis. A small well-defined mulberry like nodule measuring ~2 cm is seen in the soft tissues of the scalp in the vertex, which is likely a sebaceous cyst.

IMPRESSION: Well-defined lesion in the roof of the third ventricle with mild proximal hydrocephalus, which is likely a colloid cyst, however, small enhancing nodular lesions seen in the roof of the lesion are atypical imaging features of a colloid cyst.