Ring-shaped lateral ventricular nodules (RSLVNs) are small nodular ring-shaped lesions attached generally to the ependyma of the roof and body of the lateral ventricles.
They are incidental findings and are of no reported clinical significance 1.
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Epidemiology
These nodules are rare and their prevalence is estimated between 0.023% and 0.45% 1,2.
Clinical presentation
They are thought to be asymptomatic and are not expected to be of any practical or clinical significance 3.
Pathology
The precise nature of these nodules remains unknown due to the insufficient histopathological data 1.
Some authors have reported that these lesions represent variants of subependymomas with a peculiar imaging appearance 3.
Radiographic features
MRI
These nodules present with a characteristic thick ring peripheral portion and are generally round-shaped, but they can also be oval or even lobulated, Their size should not exceed 10 mm in diameter 1.
They are located anywhere in the lateral ventricles but they are more likely to be attached to the ependyma of the roof and body of the lateral ventricles.
The number of nodules varies, but the majority of patients present with only one nodule 1.
Follow-up does not show interval growth 2.
- signal intensity of the core portion 1
- T1/T2/FLAIR: isointense to CSF
- T1 C+ (Gd): non-enhancing
- DWI/ADC: isointense and no restricted diffusion
- signal intensity of the peripheral ring
- T1: isointense relative to the grey matter
- T2/FLAIR: iso or hyperintense relative to the grey matter intensity
- T1 C+ (Gd): non-enhancing
- DWI/ADC: isointense and no restricted diffusion
History and etymology
This entity was first described by Shimono et al in 2009 2.
Differential diagnosis
The differential is that of small lateral ventricles nodules:
-
subependymal grey matter heterotopia
- the signal intensity: isointense to grey matter
-
subependymal hamartomas
- seen in patients with tuberous sclerosis
- seizures, facial lesions, and mental retardation
- variable signal intensity and calcifies often
- they are generally located near the caudate nucleus and the interventricular foramen
- subependymal giant cell astrocytoma
- subependymomas