Middle ear adenomatous tumor: a not so rare glomus tympanicum-mimicking lesion

Middle ear adenomatous tumors (MEAT) are rare tumors which can be begin or malignant and can present a neuroendocrine differentiation. Their radiological aspect is very similar to glomus tympanicum (GT) which are the most common tumoral lesions of the middle ear. We present several radiological and clinical findings that could help radiologists to accurately identify MEAT.

We retrospectively reviewed the radiological and clinical findings of three patients with MEAT and of eight patients with GT. Diagnostic was obtained after surgical resection in all cases. All patients had high resolution CT and MR of the middle ear associated with a subtracted digital carotid angiography. Tumor location, size, extension, signal intensity, and enhancement were analysed. From the medical records of the patients, clinical manifestations (hearing loss, tinnitus), evolution length and recurrences were noted.

MEAT and GT appeared as tissular lesion with significant enhancement on CT and MR. A vascular blush was present on angiography in all cases of GT and absent from all cases of MEAT. A close relationship between the tumor and the Jacobson's nerve or its branches was identified in all cases of GT. Pulsatile tinnitus was present in all patients with GT and absent in all patients with MEAT.

A middle ear tissular lesion clearly separated from the Jacobson nerve or its branches, showing significant enhancement after contrast medium injection but with a normal angiography, should make one suspicious for MEAT.