Intravascular papillary endothelial hyperplasia arising within a posteroinferior cerebellar artery aneurysm: Case report and review of the literature

OBJECTIVE AND IMPORTANCE: Intravascular papillary endothelial hyperplasia ( IPEH) is an atypical proliferation of endothelium that results in abnormal organization for thrombus formation. Intracranial IPEH is a rare entity and has not been reported to arise from within an intracranial aneurysm. Furth ermore, the elapsed time during which acquired intracranial IPEH develops h as not been previously documented. CLINICAL PRESENTATION: In this case report, a patient with facial and neck pain was noted to have an enhancing mass lesion lateral to the medulla in m agnetic resonance imaging scans. Angiography revealed a vascular mass adjac ent to the posteroinferior cerebellar artery. Normal magnetic resonance ima ging and magnetic resonance angiographic findings had been obtained for the patient 29 months earlier. INTERVENTION: During surgery, a thrombosed, 2.5-cm, posteroinferior cerebel lar artery aneurysm was resected and noted to contain florid IPEH. There ha s been no evidence of recurrence in 1 year of follow-up monitoring. A liter ature search revealed 13 cases of intracranial IPEH, in which recurrence wa s observed for incompletely resected lesions. CONCLUSION: IPEH can develop in a relatively short time, can present as a h ypervascular mass lesion or within an intracranial aneurysm, and should be completely resected to prevent recurrence.