Lipomatous meningioma

Last revised by Frank Gaillard on 24 Dec 2021

Citation, DOI, disclosures and article data

Citation:

Gaillard F, Weerakkody Y, Adams M, Lipomatous meningioma. Reference article, Radiopaedia.org (Accessed on 18 Apr 2024) https://doi.org/10.53347/rID-42268

DOI:

https://doi.org/10.53347/rID-42268

Permalink:

https://radiopaedia.org/articles/42268

rID:

42268

Article created:

13 Jan 2016, Frank Gaillard ◉ ◈

Disclosures:

At the time the article was created Frank Gaillard had no recorded disclosures.

View Frank Gaillard's current disclosures

Last revised:

24 Dec 2021, Frank Gaillard ◉ ◈

Disclosures:

At the time the article was last revised Frank Gaillard had no recorded disclosures.

View Frank Gaillard's current disclosures

Revisions:

4 times, by 3 contributors - see full revision history and disclosures

Systems:

Central Nervous System

Synonyms:

Lipomeningioma
Lipoblastic meningioma

Lipomatous meningiomas are rare histological variants of meningiomas, accounting for only 0.3% of all meningiomas ³.

Although reported numbers are too small to confirm that this is definitely the case, they appear to share similar epidemiology, clinical presentation and treatment and prognosis as other meningiomas, and thus these features are not repeated here.

Lipomatous meningiomas are considered a type of metaplastic meningioma in the 5th edition (2021) WHO classification of CNS tumors. Although the tumor cells have appearances of mature adipose tissue, there is evidence that in most instances, they represent an accumulation of lipids within meningothelial cells rather than true metaplasia into adipose tissue ^1-3.

Radiographic features

Radiographic features depend on the amount of fat present within these tumors. When the amount of fat is small, these tumors are indistinguishable on conventional imaging from the more common conventional types of meningioma, and thus this is not repeated here.

When fat is abundant, then they deviate from the normal appearance in line with the presence of fat.

CT

Lipid rich lipomatous meningiomas are of lower density than conventional meningiomas (which are usually isodense or slightly hyperdense to brain parenchyma). In such cases they have density measurements as low as -50 to -100HU ¹. Such low-density tumors do however usually have some enhancing components and share some of the morphological features of meningiomas (e.g. dural tail)

MRI

Lipomatous meningiomas with abundant fat will have fat-like signal:

T1: hyperintense
T2: hyperintense
Fat saturated sequences: will demonstrate signal loss
T1 C+: heterogeneous enhancement

Differential diagnosis

Lipomatous meningiomas with little lipid accumulation will be indistinguishable from typical meningiomas and thus share their differential diagnosis. On the other hand, lipomatous meningiomas with abundant fatty material will have a very different differential diagnosis consisting of:

intracranial lipoma
- homogeneous fat
- no enhancement
- located within the subarachnoid space, often in basal cisterns or in a pericallosal location
intracranial dermoid cyst
- can rupture with subarachnoid droplets of fat
- no solid enhancing component (if present consider mature teratoma)
xanthomatous meningioma
- indistinguishable (?) ^{[ref needed]}
osseous meningioma
- fat signal/density will be confined to the 'medullary cavity' of ossification (thus abundant peripheral calcification)
intra-axial tumors (rarely can have fatty metaplasia/signal intensity)
- glioblastoma (GBM)
- pleomorphic xanthoastrocytoma (PXA)
- metastatic mucinous carcinoma