Epidermoid cyst is the 3rd most common cerebellopontine angle tumor after schwannoma and meningioma. The closest differential of an epidermoid cyst is an arachnoid cyst and DWI and ADC sequences are useful in distinguishing between these two lesions. An arachnoid cyst shows no restriction of diffusion whereas an epidermoid cyst does. The ADC of arachnoid cyst is similar to stationary water, whereas the ADC of epidermoid is similar to the brain parenchyma.