The patient went on to have a craniotomy and histology confirmed the diagnosis of a medulloblastoma, with typical 'small round blue cell' tumor appearances. 

The location and appearances are also typical of a medulloblastoma in an adult. 

It is important to remember that in older children and adults such tumor is more likely to be poorly marginated and demonstrates larger cyst formations. Adult medulloblastomas are usually located laterally, in the cerebellar hemispheres, with only 28% centered in the vermis (opposed to ~75% in children).