Lipoma

Incidence

Intracranial lipoma is rare.

Origin

Intracranial lipoma is not a real tumor, but a congenital malformation. It results from abnormal persistence and maldifferentiation of the meninx primitiva, which is the mesenchymal precursor of the meninges.

Macroscopic appearance and general characteristics

Most lipomas are so called lipomas of the corpus callosum.

There are two types of lipomas of the corpus callosum.

The majority of lipomas (45% to 80%) are intrahemispheric. The tubulonodular lipomas are round or cylinder-shaped lesions, frequently associated with congenital anomalies, such as agenesis of the corpus callosum. They are anteriorly situated. Curvilinear lipomas are thin and curve around the corpus callosum, which is normal or minimally dysplastic. They are posteriorly situated. Finally, small fatty lesions can be seen on the surface of the brain in the quadrigeminal, suprasellar and cerebellopontine angle cistern.

In about 36% of the cases, intracranial nerves and vessels course through the lesion. Calcification is common.

Microscopic appearance (image 2)

They are masses of fully differentiated adipose tissue, with or without a component of fibrous or vascular tissue.

Imaging features (see case reports)

- On plain CT ,

lipoma displays a very hypodense appearance with negative attenuation values of -50 to -80 HU. Curvilinear calcification is frequent. Choroidal extension of callosal lipomas is frequent.

- On MRI,

lipomas have short T1 and T2 relaxation times, appearing bright on T1 weighted images and hypointense on T2 weighted sequences. The choroidal extension and the pericallosal development are well displayed on multiplanar imaging (image 3). Calcification is seen as curvilinear black areas and has to be differentiated from flow void in vessels traversing the lesion.

Case reports

Search:
Tubulonodular lipoma with intraventricular components
Tubulonodular lipoma, calcified
Curvilinear (pericallosal) lipoma
Lipoma of the quadrigeminal plate cistern
Lipoma of the cerebellopontine angle

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