Residual cholesteatoma of the mastoid cavity presenting with radiologic signal of a cholesterol granuloma: A case report

Cholesteatoma and cholesterol granuloma can both occur in the temporal bone. Their distinct magnetic resonance imaging (MRI) signals are generally used to help differentiate one from the other to plan appropriate treatment, which differs based on the pathology.Case presentation: We present a patient with recent-onset facial paralysis whose mastoid cavity was filled with tissue radiologically resembling cholesterol granuloma but that turned out to be cholesteatoma upon surgical exploration. Complete disease extirpation was thus completed rather than simple marsupialization, the latter of which would have been sufficient in the case of cholesterol granuloma.Discussion: Cholesteatoma, although usually hypointense on T1-weighted imaging (T1WI) MRI, hyperintense on T2-weighted imaging (T2WI) MRI and showing diffusion restriction on diffusion-weighted imaging can occasionally present with an atypical MRI signal, for example, one suggestive of cholesterol granuloma.Conclusions: The clinician should keep in mind the possible diagnosis of cholesteatoma despite an atypical MRI signal in the temporal bone.