It is ambiguous whether a congenital cholesteatoma and a intradiploic epidermoid cyst are same disease entity or not. Some authors used the term congenital cholesteatoma as a broader definition to include all epidermoid cysts in the central nervous system, as there is no histopathological difference between congenital cholesteatoma and epidermoid cysts. However, some others insisted that they do differ radiologically and clinically. A 69-year-old woman presented with chronic otorrhea and a recent (3 days) onset of headache. Based on radiologic imaging results, operative findings and clinical features, a mastoid temporal bone congenital cholesteatoma expanded to posterior cranial fossa was diagnosed. This is a first documented case of a congenital cholesteatoma of mastoid temporal bone that expanded to posterior cranial fossa, which was successfully treated with transmastoid marsupialization without craniotomy.