Staged Management of Intracranial Masson Tumor: An Unexpected Gauntlet: Case Report and Review of the Literature.

Background: Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson tumor, is a benign lesion consisting of a reactive proliferation of endothelial cells with papillary formations related to thrombi. It has been reported in many different anatomic areas. Gross total resection is the elected treatment. Intracranial IPEH is rare, and only a few cases have been reported. This article reports a complicated case of cavernous sinus Masson tumor.

Case Description: A 51-year-old woman presented because of hemicraneal headache, left facial paresthesia, and diplopia (due to a slight left ocular external rectum muscle paresis) that she had experienced the previous 60 days. She had previously received a diagnosis of neurofibromatosis type I. Contrast-enhanced magnetic resonance imaging showed a 3.5-cm contrast-enhanced tumor adjacent to the left cavernous sinus involving the Meckel cave that extended around the distal petrous portion of the left internal carotid artery. Two possibilities as a differential diagnosis were suggested: meningioma or neurogenic tumor. After a staged surgical procedure, the histopathologic findings were unexpected and showed IPEH (Masson tumor) as the cause of the mass. Despite having benign features, the IPEH showed recurrences over time, so adjuvant 3-dimensional conformal radiation therapy was initiated.

Conclusions: IPEH is prone to recurrences after subtotal resection. In the present case, successful surgical treatment and adjuvant radiotherapy showed an excellent outcome. To date, no adjuvant therapy has been established as a go-to option.