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Radiation induced meningiomas and cavernous malformations

Case contributed by Derek Smith
Diagnosis certain

Presentation

Acute presentation with two episodes of left arm sensory disturbance. Any evidence of stroke / TIA?

Patient Data

Age: 55 years
Gender: Male

Hyperintense extra-axial mass, with base along the left falx. Ill defined margin with underlying brain, with some adjacent abnormal attenuation in left superior frontal / cingulate gyri.

Established left cerebellar lacune.

This lesion was considered to be a meningioma, with further imaging by contrast enhanced MRI recommended, however this location would not account for the described left body symptoms.

As identified on CT there is a 17 mm left parafalcine enhancing mass. This has a slender dural tail. Subcortical edema in the left superior frontal and cingulate gyri.

There is also a 33 x 13 mm right parietal convexity mass - which on review of the CT is of very similar density to the adjacent brain. There is dural thickening under most of the right parietal and temporal bones. This is directly in contact and displacing the right post central gyrus / sensory strip, which is likely contributing to the presentation, but there is no edema or parenchymal signal change.

No other meningiomas. The two supratentorial lesions do not demonstrate calcification on the SWI sequences.

There is minor calcification associated with the left cerebellar lacune.

However there are also a number of cavernous malformations / cavernomas, with high signal matching blood vessels on the phase part of the SWI sequences. Locations include the left frontal pole, right caudate head, right temporal stem and right operculum.

Further history confirmed that this patient had received whole brain / craniospinal radiology in childhood, with previous diagnosis of a treated pediatric monoblastic leukemia.

The patient proceeded to surgery for both the symptomatic right convexity and the left parafalcine meningioma with the brain reaction.

Pathology

Right convexity - meningothelial meningioma, WHO grade 1:
Cellular moderately pleomorphic meningothelial cells. Lobular growth pattern. Rare mitotic figures (1/10). No necrosis or brain invasion.

Left parafalcine - atypical meningioma, WHO grade 2:
Mixed lobular / fascicular growth pattern, collagenised stroma, microcystic change and thick walled hyalinised blood vessels. Scattered psammoma bodies. Occasional mitotic figures (2/10). No intrinsic necrosis. Parenchyma flanks the tumor and brain invasion is identified.

Case Discussion

There are a number of interesting learning and review points for this case.

Finding one lesion on CT should always push you to investigate for another - especially if it doesn't match the described symptoms. The large right meningioma was really difficult to discriminate from brain on the CT.

MRI showed not only the multiple meningiomas, but also a number of cavernomas. This can be seen with previous radiotherapy. This was confirmed on further patient history. It is an important finding, especially if future radiotherapy is planned for management as doses / treatment contours may need to be altered.

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