Unusual lesions of the internal auditory canal

Abstract

Acoustic neuromata (AN) account for nearly 90 per cent of internal auditory canal (IAC) and cerebello-pontine angle (CPA) tumours. The second most common tumour is meningioma. Rare lesions include primary cholesteatoma, facial neuroma, lipoma, angioma and various cysts.Two cases of IAC tumour are presented, one of hamartoma in which smooth muscle was prominent and the other of lymphangioma. Of interest are the specific clinical and radiological features associated with these lesions.

Rare Bilateral Lipoma of the Internal Auditory Canals

“…Patients reported with lipomas generally present with the same clinical symptoms as those with vestibular schwannomas 13 when they are symptomatic. The same is true for other rare lesions of the IAC and CPA 25 . Clinical diagnosis is therefore non-specific.…”

Neuromuscular Choristoma of the Internal Auditory Meatus

“…All patients suffered from a hearing loss with the exception of 1 patient with hyperacusis and 2 additional patients in whom the hearing status was not reported. Two of the patients with hearing loss presented additionally with tinnitus, 1 patient reported additionally the loss of balance and another patient tinnitus and the loss of balance [3,4,5,6]. …”

“…No growth at all or very slow growth is the typical behavior. Comments on the progression as well as spontaneous remission after incomplete removal can be found, but the dynamic behavior of choristomas in the IAM has not been reported [3,4,5,8]. The only way to monitor the growth of tumors in the IAM is serial MRI scans.…”

“…Other tumors located in the IAM are facial nerve schwannomas, hemangiomas, meningiomas, lipomas, melanomas, osteomas, metastases and lymphomas [2]. Choristomas of the 8th cranial nerve are very rare lesions with only 14 reported cases to date [3,4,5,6]. Most of them have been misdiagnosed preoperatively as VS [3,4,5,6], which is not surprising due to the much higher incidence of VS, the similar clinical presentation of the two tumors, and because a preoperative biopsy of a lesion in the IAM is not feasible.…”

Arachnoid cysts confined to the internal auditory canal or facial nerve canal

“…[1][2][3] They constitute only 0.5 per cent of all neoplasms found in these locations. [1][2][3] They constitute only 0.5 per cent of all neoplasms found in these locations.…”