Meningioma: inferior edge of falx
Fall. Headache. CT demonstrated an apparent mass.
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3.8 x 4.8 x 3.5 cm circumscribed rounded mass of homogenous intermediate T2 signal is isointense to grey matter on T1 sequences with vivid homogenous enhancement. No significant blooming artefact is identified within the lesion, but there is intense diffusion restriction.
The mass appears to arise from the free edge of the falx in the interhemispheric fissure, causing inferior displacement/indentation and gross thinning of the mid to posterior body and splenium of corpus callosum. The posterior margin of the mass is located just anterior to the straight sinus, which contains air preserved flow void. No evidence of invasion or occlusion of the inferior sagittal sinus. There is no mass effect upon the tectal plate or evidence of narrowing of the cerebral aqueduct. The right lateral ventricle is obstructed at the level of posterior body with asymmetric mild enlargement of the temporal horn.
Scattered tiny T2 hyperintense foci in the frontal white matter bilaterally may be due to mild for age chronic microvascular ischemia be due to migraines. Remainder of brain parenchyma is within normal limits, with no diffusion restriction or susceptibility artefact.
Interhemispheric mass inferiorly displacing and flattening the corpus callosum and entrapping the right lateral ventricle trigone and temporal horn has imaging morphology most consistent with a meningioma arising from the free edge of the falx.
The patient went on to have the mass resected with no complication.
MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of a moderately hypercellular meningioma. This has a mixed syncytial and fibroblastic architecture. Scattered calcified psammoma bodies are also noted. Tumour cells have uniform nuclear features. No mitotic figures or areas of necrosis are identified and there is no evidence of brain invasion.
DIAGNOSIS: Meningioma (WHO Grade I).
Fairly typical appearances of a meningioma in a slightly atypical location. Careful examination of the sagittal sequence is very helpful in determining location and thus origin / attachment.