Abstract
Middle ear cholesteatomas developed in dizygotic twins. In three of the four ears cholesteatomas developed as a result of longstanding otitis media with effusion. In the remaining ear, no cholesteatoma has been formed so far, in spite of severe eardrum retraction. The differences in the clinical course showed that not only Eustachian tube dysfunction but also blockade of the ventilation pathway between the mesotympanum and the epitympanum may play an important role in the development of cholesteatoma. High resolution CT is very useful in the diagnosis of this blockade. More dizygotic and monozygotic twins with cholesteatoma should be studied to decide whether hereditary factors have any significant influence on the occurrence of this disease.
