Intraventricular Masson tumor: case report and systematic review of primary intracranial intravascular papillary endothelial hyperplasia.

Intracranial Masson tumor (intravascular papillary endothelial hyperplasia, IPEH) is a benign lesion that is thought to originate from a reactionary process in response to compromised blood flow. IPEH may be classified into one of three subtypes based on etiology as it may result from the excessive proliferation of endothelial cells within a normal vessel (primary), vascular malformation (type II), or organized hematoma (type III). We report the case of a 79-year-old woman who presented with confusion, gait instability, and urinary incontinence. Neuroimaging revealed a hemorrhagic lesion within the right lateral ventricle, which was successfully resected. To our knowledge, this is the first reported case of an intraventricular IPEH and 33rd case of primary intracranial IPEH. We further performed a systematic review of the literature on all prior type I intracranial IPEH cases and discuss the importance of long-term follow-up in intracranial IPEH.