A Case of Congenital Open-Type Cholesteatoma Diagnosed by Diffusion-Weighted MRI Using the PROPELLER Technique

Congenital cholesteatoma in the tympanic cavity can be divided into two types - the closed-type cholesteatoma, which takes the form of a keratotic cyst, and the open-type cholesteatoma, characterized by a flat surface of the epidermis on the middle ear mucosa. Closed-type cholesteatoma is usually identified as a globular white mass through a normal tympanic membrane; whereas the tympanic membrane appears normal in open-type cholesteatomas. Therefore, it is difficult to diagnose open-type cholesteatomas, which are often identified accidentally during exploratory tympanotomy for preoperative diagnoses such as conductive hearing loss. Herein, we report a case of open-type cholesteatoma, in which the diagnosis was suspected from the findings of diffusion-weighted MRI examination using the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique.