Acquired cholesteatoma is the most common type, and it can be caused by a tear or retraction of the eardrum. Acquired cholesteatomas usually arise from the pars flaccida region of the ear in the posterior-superior area of the eardrum.

Congential cholesteatoma is less common. They are most often found in the anterior area of the eardrum and are often diagnosed early in life. People with congenital cholesteatoma are born with this condition. 

Treatment Options
Congenital cholesteatomas of the middle ear can be removed through the ear canal. Most cholesteatomas require that an incision be made behind the ear to expose the affected area and allow for full removal. These masses are not cancerous but must be removed to prevent the delicate tissues of the ear from being severely damaged.