This case demonstrates typical appearances of a colloid cyst. 

This case elegantly illustrates two potential traps of interpreting MRI signal intensities:

1. just because a cystic structure appears to have CSF signal on FLAIR does not mean that this is true - in this case the content is very T2 hypointense
2. density of MRI is relative, not absolute (unlike CT) and thus care should be taken when interpreting post contrast sequences - note how in this case the center of the cyst appears less bright than pre-contrast