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Colloid cyst

Case contributed by Thành Anh Lê
Diagnosis almost certain

Presentation

Headache. No history of injury.

Patient Data

Age: 55 years
Gender: Male

Head 1.5T

mri

The MRI reveals the presence of a rounded lesion located at the right foramen of Monro. These lesion demonstrates isointensity to the adjacent brain tissue on T1W and T2W imaging and shows high signal intensity on FLAIR imaging. There is no evidence of restricted diffusion or dark signal on SWI. Following administration of contrast, thin peripheral enhancement is observed. These lesion have resulted in obstructive hydrocephalus and mild transependymal edema within the right lateral ventricle

Head CT after surgery

ct

After neurosurgery, CT shows pneumocephalus and subdural hematoma.

Case Discussion

On imaging, we're not entirely sure about the diagnosis of a colloid cyst in this case.

  1. the lesion is not located in the middle of the foramen of Monro which is the reason for the obstructive hydrocephalus in the right lateral ventricle

  2. the lesion demonstrates an isointense signal on both T1W and T2W images, which is not a typical appearance of a colloid cyst

Therefore, we suggest considering an alternative diagnosis: subependymal giant cell astrocytoma.

However, the size of the lesion (<1cm), the lack of calcification (no dark spot on SWI), and surrounding thin enhancement (represents an enhancement of the adjacent and stretched septal veins) lead us to disagree with the possibility of subependymal giant cell astrocytoma (SEGA). 

Consequently, we ultimately concluded that a colloid cyst is the most likely diagnosis in this situation. 

The patient underwent surgical resection, and the pathology confirmed the diagnosis.

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