We report on the case of a 33-year-old woman complaining of tinnitus and hearing loss
up to 60 dB in the low frequencies of the right side. Vertigo was negated but videonystagmography
revealed a complete loss of function on the right side.
T2-weighted magnetic resonance imaging showed a contrast enhancement in the right
lateral semicircular canal. In our interdisciplinary neuroradiological conference
this was diagnosed to be an acoustic neuroma.
4 years later, the patient showed up again with right-sided deafness. The MRI scan
showed the same lesion without progression, still consistent with an intralabyrinthine
acoustic neuroma. The patient was fitted with CROS hearing aids because of her regular
hearing on the contralateral ear.
Due to insufficient hearing benefit, a translabyrinthine resection with simultaneous
cochlea implantation was performed. Intraoperatively the tumor extension was limited
to the vestibulum. The middle ear as well as the inner ear canal were not affected.
The preliminary pathological examinations revealed a tumor with high cellularity,
which was suspected to be a paraganglioma. After multiple immunohistochemical staining
the tumor finally was classified as an intralabyrinthine middle ear adenoma with expansion
into the cancellous bone.
Adenomas of the middle ear are rare benign neoplasms arising from the middle ear mucosa.
Due to uncharacteristic symptoms and unspecific medical complaints, they are often
misdiagnosed. In imaging, these adenomas are hard to distinguish from other tumors.
Complex immunohistochemical staining is often necessary to confirm the diagnosis.
An intralabyrinthine middle ear adenoma is an absolute rarity and therefore a diagnostic
challenge.
