Abstract
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.
An 18-year-old male presented to our hospital with the complaint of right hearing loss, which was suspected at a previous ENT clinic to be caused by a congenital ossicular anomaly. Otoscopic examination failed to reveal any abnormalities. Pure-tone audiometry showed moderate conductive hearing loss in the right ear. Computed tomography of the temporal bone revealed a defect of the long process of the incus and superstructure of the stapes, with a surrounding shadow that appeared to be soft tissue. On the basis of these findings, we suspected an open-type cholesteatoma with a defect of the ossicles. Diffusion-weighted MRI examination using the PROPELLER technique showed a high-intensity in the temporal bone, suggestive of a cholesteatoma. We performed exploratory tympanotomy, and found the open-type cholesteatoma in the middle ear. The cholesteatoma was removed without ossiculoplasty, and until now, nine months after the surgery, there has been no sign of recurrence.
Our case showed the usefulness of diffusion-weighted MRI using the PROPELLER technique for the diagnosis of the open-type cholesteatoma. The possibility of open-type cholesteatoma should be borne in mind in patients diagnosed preoperatively as having a congenital ossicular anomaly, and diffusion-weighted MRI with the PROPELLER technique is indicated in such patients towards confirming the diagnosis.
