Keywords: epidermoid cist, retrocochlear hearing loss, retrocochlear tumors

Abstract: The case presented is of a 16-year-old pacient that had as unique complaint a profound left hearing loss for about seven years. The M.R.I. showed a cistic mass on the Internal Acoustic Meatus and Posterior Fossa with displacement of the Brain Stem. The electrophysiologic evaluation of the hearing (BERA, OAE) had established the retrocochlear involvement. After the surgery procedure, the histogical finding was an Epidermoid Cist. Those cists are rare tumors from ectodermic nature that must be considered as a differential diagnosis of thé retrocochlear hearing loss.