
52 y.o. man with difficulty walking, memory problems, incontinence; history of colon cancer
Ataxic gait
Colloid cyst with obstructive hydrocephalus
Unenhanced head CT demonstrating a hyperattenuating midline lesion obstructing the lateral ventricles at the foramina of Monroe. Periventricular white matter hypoattenuation suggests transependymal CSF migration.
Head CT demonstrates hyperattenuating mass in the midline at the foramina of Monroe. The mass is causing obstructive hydrocephalus of the lateral ventricles with transependymal CSF migration.
• Colloid cyst
• Cysticercosis
• Ependymoma
• Central neurocytoma
Dx: Colloid (neuroepithelial) cyst of the third ventricle
Dx Confirmed by: Neurosurgical resection
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Patient’s symptoms resolved; no known recurrence after neurosurgical resection.
A colloid cyst is a non-malignant epithelial-lined cyst that most commonly arises in the midline brain in the anterosuperior aspect (roof) of the third ventricle. This lesion is classically non-enhancing and hyperattenuating on head CT, but the imaging appearance can be variable depending on the internal cyst contents and capsular vascularity. Small colloid cysts filled with CSF may be easily overlooked on CT/MRI exams of the brain.
When large enough, colloid cysts can obstruct the foramina of Monroe, as in this case. As a consequence, presenting symptoms would include personality disturbances, ataxia, and incontinence (“wacky, wobbly, and wet”). A similar entity that can produce these same symptoms is normal pressure hydrocephalus (NPH).
As there is a risk of sudden death, neurosurgical treatment is suggested. Options include VP shunting, complete cyst resection, or stereotactic aspiration; however, recurrences can occur with aspiration alone. Spontaneous rupture can occur without treatment, but neurosurgical care is recommended.
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