Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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May 16, 2019
Lipomatous meningioma
- Background
- Lipomatous meningiomas are a rare variant of meningiomas, making up only 0.3% of all meningiomas. They are classified as metaplastic meningiomas according to the World Health Organization (WHO) classification (subtype of WHO Grade 1 meningioma).
- This is due to the initial thought of metaplasia of meningothelial cells into adipocytes. However, recent evidence suggests it could, in fact, be due to lipid accumulation within the meningothelial cells, rather than actual metaplastic transformation into adipocytes.
- Clinical Presentation
- Clinical presentation can range from asymptomatic incidental finding for smaller tumours to headache, paresis, change in mental status, visual field / cranial nerve defects and hydrocephalus. The mean age of presentation is 50 years with a range of 22-74 years.
- Key Diagnostic Features
- Radiological features will depend on the quantity of fat within the tumor. With larger amounts of fat, these lesions will appear hyperintense on T1 and T2-weighted imaging. They will demonstrate loss of signal on fat-saturated signal and show contrast enhancement.
- Further standard features of meningioma such as dural tail and bony hyperostosis can be present.
- On CT, the tumour appears as hypodense to isodense lesions, which enhance with contrast and demonstrate similar characteristics to standard meningiomas.
- Differential Diagnosis
- Intracranial lipomas: Can appear similar but do not show any contrast enhancement and are often located within the subarachnoid space.
- Dermoid cysts: Often more heterogeneous lesions with solid areas, contain fat and calcification. They also tend to be located in the midline.
- Both lipomas and dermoid cysts do not have a meningeal component and thus do not demonstrate a dural tail or bony hyperostosis.
- Xanthomatous meningioma: It is not possible to differentiate this from a lipomatous meningioma.
- Treatment
- The treatment options are similar to standard meningiomas and include conservative management with a monitoring approach or surgical excision.
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