Neuroepithelial cysts are rare, representing less than 1% of the intracranial cysts. Neuroepithelial cysts, are benign and mostly asymptomatic. These cysts are lined by thin columnar or low cuboidal epithelium. The CSF-like contents of the cyst are due to secretion of the epithelial cyst wall. Although mostly asymptomatic, symptoms can occur when the cyst enlarges; the specific symptoms vary according to the size (mass effect) and location of the lesion. Radioactive phosphorus (32P) and 90yttrium colloid are isotopes that have been used. These are approved in the United States and Europe. 32P is not available in Canada. We want to use 90yttrium colloid. There is evidence in the scientific literature that treatment with 90yttrium colloid injected into the cyst is effective in preventing the cyst from growing, effective in causing the cyst to get smaller and in some cases the cyst disappears.

In brief, a single patient has been identified as having a cystic tumor by diagnostic imaging and clinical expertise and based on standards of excellence in clinical care will be offered participation in the study for the intracystic implantation of 90yttrium colloid. This patient will be followed closely for 4 weeks following 90yttrium colloid treatment and then receive standard of care (http://neurosurgery.medicine.dal.ca).

Inclusion criteria:

1. Cystic tumor
2. Required treatment
3. Adult over 17 years of age
4. Willingness to provide informed consent

Exclusion criteria

1. Solid tumor
2. Treatment not required
3. Child under 17 years of age
4. Not willing to provide informed consent