Pericavernous sinus Masson's tumor

Case contributed by Ralph Nelson


New onset left optic neuropathy, atypical.

Patient Data

Age: 70 years
Gender: Female

Moderaly spontaneously hyperdense left pericavernous mass. Bone remodeling without associated bone erosions. Left scleral buckle is seen.

Approximately 3 x 2 x 3 cm extra-axial left sided pericavernous mass along the medial surface of the left temporal lobe causing marked compression of the left optic nerve within the orbital apex and along its anterior intracranial portion. It abuts the left internal carotid artery without encasement or narrowing. It deviates the artery posteriorly and medially. Superiorly the mass is in direct course of the left oculomotor nerve. There is elevation of the left lateral aspect of the pituitary gland.

The mass is circumscribed and has a well-defined thin T2 dark rim along its posterior lateral aspects. It is moderately T2 bright. On post gadolinium injection the mass demonstrates progressive enhancement which begins centrally and proceeds craniocaudally.

No edema or invasive features. Normal fat preservation in the left pterygopalatine fossa.

Absent left ocular lens.

Screenshot of pathology report of confirming the diagnosis of pericavernous papillary endothelial hyperplasia aka Masson tumor.

Case Discussion

Masson’s tumors or intravascular papillary endothelial hyperplasia (IPEH) are rare nonneoplastic vascular lesions, uncommon in the central nervous system. In fact, there has been selected intracranial reported cases. Their pathogenesis remains unclear. They have been found case report of IPEH found in the larynx, cervical and thyroid region, scalp, central canal, posterior fossa, internal auditory canal, urinary bladder, etc (please refer to References for related case examples).

Viewed as a mimicker of meningiomas, Masson's tumors should be considered among enhancing intracranial vascular lesions. Resection is often curative though recurrence can happen with subtotal resection. 

Fortunately, almost 3 years post-resection, our patient remains free of tumor recurrence.  

In consideration of the rarity of this tumor, we provide this case to the Radiopedia community for help with pre-operative radiological diagnosis.

The key imaging features match those expressed on the related Radiopedia article. DWI-ADC sequences were not performed. As per literature, Masson's tumors would show mixed areas of restricted diffusion, likely owing to hyperplastic endothelial cell proliferation inducing low-ADC values versus capillary channels and hemorrhagic contents inducing no DWI restriction, which would be consistent with findings on the pathology report. The absence of cytologic features of malignancy (no necrosis nor mitosis) with the presence of CD31 staining have also been reported.

Courtesy of Profs. Rosenbloom L. and Levental M., exemplary teachers and respected radiologists.

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