Meningioma - posterior falx

Case contributed by Assoc Prof Frank Gaillard

Presentation

Headaches.

Patient Data

Age: 70 years
Gender: Male

MRI brain

MRI

 A large homogeneously enhancing lesion closely adherent to the posterior falx, eccentric to the left, is demonstrated, with moderate restricted diffusion. This lesion appears extraaxial. There is continued mass effect on the splenium of the corpus callosum, with bright T2/flair signal extending through splenium into the parietal white matter bilaterally. It is superior to the internal cerebral veins and vein of Galen. Inferior sagittal sinus is closely apposed to it superiorly. There is mass effect on the confluence of the vein of Galen and ISS. There is effacement of the trigones bilaterally without significant temporal horns enlargement.

Angiogram

DSA (angiography)

There was faint tumor blush in the region of the posterior falx post vertebral artery injection. Careful analysis showed that the arterial supply came from posterior choroidal arterial branches and deep penetrating branches of the posterior cerebral arteries. There was no arterial contribution from the middle meningeal arteries.

Given the vascular supply originated from the posterior choroidal arteries, there was no role for pre-op embolization.

Histology

Pathology

Paraffin sections show fragments of a moderately hypercellular meningioma with a well developed syncytial architecture. The tumor cells have uniform nuclear features.  No mitotic figures or areas of necrosis are identified and there is no evidence of brain invasion. 

Case Discussion

Sometimes it can be difficult to distinguish intra and extra-axial tumors, especially when they are large nestled deep in a sulcus or the interhemispheric fissure. In this case it invaginates the splenium of the corpus callosum with significant edema. 

One could be tempted to consider a GBM or even lymphoma, although on careful inspection a cleft can be seen between the mass and the adjacent corpus callosum. It is clearly remote from the pineal gland, being located above the internal cerebral veins. 

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