Metastatic Melanoma
Findings:
Multiple MR images demonstrate a large amount of acute hemorrhage within a mildly dilated ventricular system. A large focus of superimposed nodular enhancement involves the choroid plexus within the atrium of the right lateral ventricle. There is additional intense enhancement lining the right occipital horn which could represent active contrast extravasation or enhancing tissue.
Differential diagnosis and discussion:
The differential diagnosis for intraventricular hemorrhage is broad, but is narrowed significantly by the presence of an associated enhancing intraventricular mass. Intratumoral hemorrhage may be seen with choroid plexus papilloma or carcinoma but free/massive IVH would be unusual. IVH and intense uniform enhancement would also be unusual for ependymoma. The location and appearance of a solid mass with hemorrhage makes a central neurocytoma unlikely. The overall features should raise concern for a metastasis or other aggressive intraventricular malignancy. This patient has a known history of melanoma with previously treated intracranial metastases which are not shown.