Contents
Intracranial lipomas are not true neoplasms, but congenital malformations which represent persistence of menix primitiva, a mesenchymal neural crest derivative
Rare intracranial tumours and they represent only about 0.1% of all intracranial tumours
Pathophysiology
Corpus callosum agenesis or dysgenesis (M/C brain anomaly)
Site:
- Interhemisperic/pericallosal locations (45%)
- Cerebello-pontine angle (9%)
- Sylvian (5%) cisterns
Interhemisperic/pericallosal
Pericallosal lipomas can be divided into two subgroups based on relevance of their locations and severity of associated malformations.
- Tubulonodular type: Characterized by nodular lesions and associated with fronto-fascial abnormalities
- Curvilinear type: Usually asymptomatic and they can be small or extensive. Usually, they are located posteriorly, they are of sizes which are less than 1 cm and they can be associated with hypoplasia of corpus callosum
Presentation
Intracranial lipomas can be completely asymptomatic or they may be associated with a wide variety of signs and symptoms. Asymptomatic intracranial lipomas are usually incidentally detected on computed tomography (CT) or MRI.
Diagnosis
Imaging is the mainstay in the diagnosis.
Plain radiographs:
Curvilinear (bracket) calcification especially in the tubulonodular variety
- Differenential diagosis:
- Corpus callosum lipoma: Curvilinear (bracket) calcification
- Sturge Weber syndrome: Tram track calcification
- Tuberous sclerosis: Calcification of ependymal nodules in the wall of ventricles,
- Meningioma: Calcification and hyperostosis and increased vascular markings
CT scan:
Smoothly demarcated and hypodense mass with density of 50-100 negative HU. It is often marginated by nodular or curvilinear calcification
MRI:
Homogenously hyperintense lesion on both T1 and T2 weighted images, with areas of low signal intensity due to peripheral calcification. The diagnosis is often confirmed on fat suppressed images which show signal loss due to suppression of fat. Sometimes central flow voids representing pericallosal arteries coursing through the substance of tumour are seen.
T1 weighted mid sagittal MR of the brain showing a curvilinear bright hyperintense area around splenium of the corpus callosum suggestive of a lipoma, there is a thin area of signal loss around it, which represents calcification | Alam, A., Sree Ram, M. N., & Sahu, S. (2006). Lipoma of the Corpus Callosum : Diagnosis Using Magnetic Resonance Imaging. Medical journal, Armed Forces India, 62(3), 299–300. https://doi.org/10.1016/S0377-1237(06)80032-8 T1 weighted fat suppressed mid sagittal MR of the brain showing suppression of signals from the curvilinear area around the splenium of the corpus callosum which appeared hyperintense on T1 & T2 weighted images, confirming the presence of fat in the lesion. | Alam, A., Sree Ram, M. N., & Sahu, S. (2006). Lipoma of the Corpus Callosum : Diagnosis Using Magnetic Resonance Imaging. Medical journal, Armed Forces India, 62(3), 299–300. https://doi.org/10.1016/S0377-1237(06)80032-8
