Magnetic resonance imaging of a medullary dermoid cyst with secondary hydrocephalus in a dog

Magnetic resonance images were acquired of the brain of a 7-year old male G olden Retriever with hydrocephalus secondary to a medullary lesion, Images were acquired prior to and 4 weeks following surgical treatment for the hyd rocephalus, and the dog was euthanased following the second imaging session . The MR images demonstrated a medullary lesion with patchy but predominant ly hyperintense signal with both T1- and T2-weighting, within which small a reas of low signal were scattered. There was little edema associated with t his lesion and no enhancement with gadolinium. Postmortem examination revea led the medullary mass to be a dermoid cyst. Several small nodular lesions were identified within the central nervous system on the magnetic resonance images whose origin was uncertain on postmortem examination.