Description

R.R.M., female, 40 years old, presenting with severe symptoms of Temporomandibular Joint disorder, underwent Head Computed Tomography (CT) during its investigation. It revealed an incidental finding of asymptomatic pedunculated bone lesion of approximately 0,51 x 0,55 mm, originating in the inferior portion of the right Internal Auditory Canal (IAC), adjacent to the cerebellopontine angle, indicated by the yellow arrows in Figure 1, (A) and (B) in axial plane and orange arrow (C) in coronal plane. These findings are compatible with an IAC Osteoma. Osteomas are slow-growing benign bone tumors commonly observed in the temporal bone, especially in the mastoid cortex and external auditory canal. Its appearance in the IAC is very rare and is usually discovered incidentally [1]. The main differential diagnosis is with Exostosis. Unlike the Osteoma, Exostosis usually present with multiple bilateral lesions with a broad implantation base [2]. CT is the most effective diagnostic tool for this type of bone lesions [1].

Figure 1:

References

1. Suzuki J, Takata Y, Miyazaki H, Yahata I, Tachibana Y, Kobayashi T, et al. Osteoma of the internal auditory canal mimicking vestibular schwannoma: Case report and review of 17recent cases. The Tohoku Journal of Experimental Medicine. 2014; 232: 63-68.
2. Martínez DS, González IB, Iglesias PF. Osteoma del conducto auditivo interno. Acta otorrinolaringol. Esp. 2015; 364-365.