Selection of the appropriate surgical approach may pose a challenge in cases of cholesteatoma where the disease extends in an atypical direction, such as into the petrous portion. We encountered a case of cholesteatoma extending from the medial side of the mandibular fossa to the foramen spinosum. We utilized the transmandibular fossa approach and successfully removed the lesions completely, without major complications. The patient was an 80-year-old man who had undergone right-sided tympanoplasty and canal wall-down mastoidectomy in his childhood and presented to us with a history of right-sided otorrhea and sensorineural hearing loss. The tympanic membrane was adherent, primarily in the posterosuperior quadrant. The anterior wall from the mesotympanum to the epitympanum was retracted. Keratin debris discharge was observed. Computed tomography (CT) of the temporal bone showed soft tissue density areas extending from the medial side of the mandibular fossa to the foramen spinosum, associated with a bone defect in the medial wall of the mandibular fossa, tegmen and jugular fossa. We diagnosed the lesion as a recurrent cholesteatoma and scheduled surgical treatment. To secure a sufficiently wide area to remove the lesion completely, we dislocated the head of the mandible and drilled out the mandibular fossa. The postoperative course was uneventful, and no recurrence was observed until the last follow-up 8 months later. Adoption of the transmandibular fossa approach may enable a surgeon to remove middle ear lesions that extend ventrally to the foramen spinosum without sacrificing critical structures.
