Obstructing isodense colloid cyst

Case contributed by Derek Smith
Diagnosis certain


New headache last night, with vomiting overnight. Found this morning GCS 10. Minor improvement in department to 13. No focal neurology.

Patient Data

Age: 40 years
Gender: Male

Hydrocephalus of the lateral ventricles. The third ventricle is effaced, with normal cerebral aqueduct and fourth ventricle. No tonsillar descent currently.

No obstructing mass is identified on this CT, and there is no abnormal enhancement post-contrast.

No hemorrhage or infarct. The venous sinuses opacify normally.

Interval right frontal ventricular access.

12 mm colloid cyst in rood of third ventricle. T2w signal similar to CSF, with no suppression/high signal on FLAIR. Small low T2w/high T1w posterior component.

Minor reduction in size of lateral ventricles, although temporal horns are still enlarged. Periventricular high signal compatible with transependymal CSF shift,

Case Discussion

In cases with isolated lateral ventricular hypertrophy, careful examination of the foramen of Monro is essential. There may be signs of other pathologies (e.g. tuberous sclerosis with a SEGA) however colloid cysts are relatively more common and can be isodense.

Regardless, the urgent step for this patient is CSF decompression and further imaging investigations can follow.

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