Friday, 9 September 2011

Corpus callosal Agenesis with Lipoma

Non contrast CT Brain, MRI Brain Axial T1 and Sagittal T1w images

Findings are non converging, widely separated parallel lateral ventricles due to Corpus Callosal partial Agenesis better seen on MRI sagittal T1w images as splenium portion of CC is not visualized (white arrow)
There is an associated inter hemispheric lipoma with curvilinear calcification.

Related post :
Meckel's Cave lipoma
Lipoma at incisura

Intracranial lipoma 

Syn : Lipomatous hamartomas, as normally fat not present in CNS.
A congenital malformation , not a true neoplasm.
Contributes < 0.5% of all intracranial tumors.

A focal fat density (dark 'z' black) on CT or fat signal intensity (white on T1w image) and is often out standing in the background of adjacent normal dark brain parenchyma on T1w images.
Noted as an isolated incidental finding or associated with other anomalies as a part of syndrome. Most common anomaly associated is Corpus callosal Agenesis / Dysgenesis.

Most common location is supra tentorium ~80%. In that most common location is mid line along corpus callosum ~ 50%, Suprasellar cistern attached to infundibulum, hypothalamus ~ 20%,  Pineal region ~15%. Meckel's cave and lateral fissures are rare locations.
Infra tentorium contributes remaining 20%, in that common locations are Cp angles, jugular foramen and foramen magnum.

Two types of intracranial lipoma:
1. Curvilinear type is a thin stripe along CC.
2. Tubulonodular type is a bulky nodular mass, frequently show dense nodular calcifications, and often associated with Corpus callosal or adjacent parenchymal anomalies.

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