Clinical History : 60yr old female patient with right 3rd nerve palsy. Suspecting a PCom aneurysm, CT angiogram was performed which showed no intracranial aneurysms.
However a heterogenously hypodense non-enhancing lesion was seen in the right cavernous sinus, with cavernous ICA seen medially displaced. Lesion anteriorly showed markedly hypodense area of negative attenuation varying from -100 to -150HU, suggesting intralesional fat. Posterior rim of the lesion showed small calcfications. Lateral hyperdense rim was thought to represent the thickened dural layer of cavernous sinus.
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| Orange arrow points to the outer rim / dura of cavernous sinus. Green arrow points to the intralesional minimal fat. The blue arrow shows the medially displaced right cavernous ICA. |
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| ROI showing the HU value of anterior hypodense area to be -128HU (fat). |
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| Coronal sections showing the anterior fat (blue arrows). |
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| White arrow: The scalloped roof of right sphenoid sinus without destruction indicating a benign longstanding pathology. Green arrow: Displaced cavernous ICA with wall calcifications. |
Intracranial dermoid cyst is a very rare congenital tumor, location within the cavernous sinus being still rarer. Cavernous sinus dermoid cysts are usually interdural with well defined margins and rounded contour and shows T1 hyperintense, T2 hypo / mixed signal intensities. ICA is usually displaced medially.1
REFERENCES:
1. Imaging Lesions of the Cavernous Sinus, A.A.K. Abdel Razek and M. Castillo
American Journal of Neuroradiology March 2009, 30 (3) 444-452;
DOI: https://doi.org/10.3174/ajnr.A1398
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