Abstract
Congenital cholesteatoma and asymmetric fatty marrow are both common masses that appear as imaging “lesions” in the petrous apex, but their treatment modalities are very different. Accurate preoperative recognition by computed tomography and magnetic resonance imaging is, therefore, important for planning appropriate management strategies. We report a case with coexisting congenital cholesteatoma and asymmetric fatty marrow in the same petrous bone. The 2 lesions were indistinguishable on high-resolution computed tomographic images and were only identified on fat-suppressed magnetic resonance imaging sequences. This is the first report of these 2 lesions coexisting, leading to a rare misleading imaging finding.
1
Introduction
Lesions of the petrous apex include congenital abnormalities, infections, neoplasms, and obstructive processes. The 2 most common congenital lesions are cholesteatoma and asymmetric fatty marrow, which represent a true lesion and a pseudolesion, respectively. Identification of these 2 lesions is not difficult for radiologists or otologists, but the findings can be misleading when the 2 masses coexist in the petrous bone.
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Case report
A 17-year-old adolescent boy presented with progressive hearing loss for 8 years. There was no history of otitis media, but otoscopic examination revealed a white cholesteatoma behind the intact tympanic membrane. The cholesteatoma was confirmed by pathology of the following surgery. High-resolution computed tomography (CT) of the temporal bone ( Fig. 1 ) revealed 1 mass located in the supralabyrinthine region, invading into the attic and seemed extending into the petrous apex. The petrous apex on the contralateral side was well pneumatized. However, both T1-weighted and fat-suppressed magnetic resonance (MR) sequences revealed 2 distinct lesions ( Figs. 2 and 3 ). These 2 lesions were identified as a congenital cholesteatoma and asymmetric fatty marrow, coexisting in the same location. The cholesteatoma was limited to the supralabyrinthine region, whereas the lesion in the petrous apex was asymmetric fatty marrow. The use of CT imaging findings alone, without additional MR images, could have led to the diagnosis of a single lesion invading into the apex, potentially resulting in the choice of a more aggressive surgical strategy, such as a middle fossa approach. Correct identification of the 2 coexisting lesions allowed the successful removal of the masses through a transmastoid supralabyrinthine approach, which is a more familiar approach for otologists and represents a less invasive surgical procedure.
