The non-contrast images demonstrate a central large mass arising in the ventricular sytem near the foramen of Munro. There is resultant obstructive hydrocephalus. The lesion has small cystic regions and enhances avidly on contrast administration. The differential diagnosis of intraventricular lesions includes:
| Lesion Astrocytoma (including Giant Cell variant) Colloid Cysts Central Neurocytoma Choroid Plexus Papilloma Meningioma Metastases Ependymoma Subependymoma Epidermoid/Dermoids | Characteristic Feature Foramen of Munro Foramen of Munro/3rd Ventricle Septum pellucidum attachment Body/Temp Horn Trigone Trigone, Choroid Plexus 4th Ventricle 4th Ventricle Fat containing |
Of these only the first two are always located at the foramen of Munro. Colloid cysts are uniformly of increased density and usually demonstrate uniform enhancement. The lesions protrude into the third ventricle inferiorly. Presentation is later in life (3rd-4th decade). The patient in this case had cutaneous manifestations consistent with Tuberous Sclerosis. Cutaneous abnormalities are not present in colloid cysts. Central neurocytomas occur in young adults and may be located near the foramen of Munro as the lesions are characteristically attached to the septum. However, these lesions are usually coarsely calcified possibly due to the frequent intratumoral haemorrhage in these cases. The other lesions listed including meningiomas (associated with skin lesions in NF-2) do not typically occur at the Foramen of Munro. In this case the location, cysts, enhancement and the presence of skin lesions (adenoma sebaceum, shagreen patches, hypo/hyperpigmented macules) are characteristic of a supendymal giant cell astrocytoma in a patient with Tuberous Sclerosis.
Approximately 15% of patients with Tuberous Sclerosis will develop a giant cell astrocytoma during their teens or early twenties. Conversely approximately 90% of patients with this type of tumour will have tuberous sclerosis. The lesion arises invariably at the Foramen of Munro and is attached to the head of the caudate, growing into the ventricles maintaining an ependymal lining. This feature contributes to the absence of intraventricular seeding. Cysts and calcifications(50%) may occur. Other cerebral stigmata of cerebral TS may or may not (as in this case) be present (eg. cortical hamartomas, supendymal nodules, white matter dysplasia) helping to differentiate from other tumours. The patient will, however, usually have other features of the disease. There is a slow progression to hydrocephalus and so symptoms may be surprisingly mild with apparent advanced disease. The tumours are Grade 1 and have a very good prognosis following resection.
Approximately 15% of patients with Tuberous Sclerosis will develop a giant cell astrocytoma during their teens or early twenties. Conversely approximately 90% of patients with this type of tumour will have tuberous sclerosis. The lesion arises invariably at the Foramen of Munro and is attached to the head of the caudate, growing into the ventricles maintaining an ependymal lining. This feature contributes to the absence of intraventricular seeding. Cysts and calcifications(50%) may occur. Other cerebral stigmata of cerebral TS may or may not (as in this case) be present (eg. cortical hamartomas, supendymal nodules, white matter dysplasia) helping to differentiate from other tumours. The patient will, however, usually have other features of the disease. There is a slow progression to hydrocephalus and so symptoms may be surprisingly mild with apparent advanced disease. The tumours are Grade 1 and have a very good prognosis following resection.
RSS Feed
