'Caterpillar sign' in corpus callosum associated with curvilinear pericallosal lipoma in MRI: A case report

Lipoma of the corpus callosum, also known as pericallosal lipoma, is a rare congenital brain abnormality associated with corpus callosum dysgenesis or agenesis. Two morphological types are described: tubulonodular and curvilinear, with the latter being mostly asymptomatic. We present the case of a 30-year-old woman with epilepsy, whose magnetic resonance imaging revealed a “caterpillar sign” in the corpus callosum associated with a curvilinear pericallosal lipoma. The “caterpillar sign” in the corpus callosum showed low signal intensity on magnetization prepared rapid acquisition with gradient echo, high signal on fluid-attenuated inversion recovery, and low on susceptibility-weighted imaging, possibly indicating abnormal blood vessels penetrating from the ventricle to the posterior callosal vein. We need to be conscious of this unusual finding, particularly when considering surgical intervention in the corpus callosum in cases of pericallosal lipoma, to avoid vascular complications.