Clinical and Radiological Characteristics of Malignant Tumors Located to the Cerebellopontine Angle and/or Internal Acoustic Meatus.

OBJECTIVE: Metastatic lesions to the internal auditory meatus (IAM) and/or the cerebellopontine angle (CPA) are rare and may appear like a vestibular schwannoma (VS). We herein raise the issue of the diagnosis and treatment of nine malignant cases of the CPA and IAM among three referral centers in France and Japan. The aim of this study was 1) to report malignant lesions of the CPA, their diagnosis and treatment, 2) to review the literature, 3) to propose criteria of suspicion for malignant tumors of the CPA.

METHODS: Nine patients who had malignant lesions of the CPA and/or IAM for whom the final diagnosis was made by surgery, lumbar puncture, or PET scan were included. The main outcomes measured were: rapid onset of symptoms, association of cochlea-vestibular symptoms with facial palsy, and MRI analysis.

RESULTS: Among the nine patients with malignant tumor of the CPA, 8 of them (89%) had a facial palsy associated with cochlea-vestibular symptoms. Rapid growth of the tumor was observed in 77% (7/9) of the cases in a mean time interval of 4.6 months. The initial diagnosis evoked was VS in 44% of the cases (4/9). Atypical MRI aspect was seen in 67% of the cases (6/9) with bilateral tumors in 55% of cases (5/9).

CONCLUSION: Although rare, malignant tumors of the CPA and/or IAM should be evoked in case of association of cochleovestibular symptoms and facial palsy, rapid onset and atypical MRI aspect.