Lesions of the corpus callosum are uncommon and arise from multiple different etiologies. The lesions can be classified according to underlying pathophysiology 4-6.
Neoplasm
Typically, amongst neoplasms, only aggressive lesions can invade the corpus callosum as it is composed of very dense white matter tracts which act as a barrier to tumor spreading 1.
meningioma: secondary involvement from primary falx lesion
metastasis: rare, mainly from contiguous extension of lesion adjacent to corpus callosum
Vascular
aneurysm: can occasionally rupture into the corpus callosum
arteriovenous malformation: arising around the corpus callosum
cavernous malformation (cavernoma)
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gliosis: secondary to small vessel chronic ischemia, subcortical arteriosclerotic encephalopathy, radiation therapy and normal aging 11; histologically corresponds to subependymal gliosis
the subependymal splenium is typically affected with normal aging and after radiation therapy 11
hypoxic-ischemic encephalopathy: corpus callosum only involved in severe or advanced case
infarction: rare because of extensive collateral vascular supply, most often seen with emboli, major ischemic stroke, subfalcine herniation with mass effect and vasculitides 3
Infection
aspergillosis: can involve corpus callosum 7
transient lesions of the splenium: many underlying etiologies including infectious agents
subacute sclerosing panencephalitis: can involve the corpus callosum in advanced stages 8
tuberculosis: callosal tuberculomas have been reported, although rare 9
Demyelination
Marchiafava-Bignami disease: demyelination and necrosis, can appear as cystic lesions
Leukodystrophy
Congenital
tubonodular pericallosal lipoma: associated with dysgenesis of the corpus callosum
Trauma
Other
cytotoxic lesions of the corpus callosum (CLOCCs): many underlying etiologies
posterior reversible encephalopathy syndrome (PRES): callosal involvement seen in up to 10% of patients, usually with associated parieto-occipital T2-hyperintensities 10
post shunt decompression: after placement of ventriculostomy in patients with chronic hydrocephalus