A 60-year-old male patient presented with complaints of hearing loss, balance disturbance, and headache, with related findings on physical examinations. Neuroradiological evaluation showed a left-sided extra-axial mass lesion of the cranial nerve VII/VIII complex in the cerebellopontine angle. The patient was operated with preliminary diagnosis of acoustic neuronoma. Intraoperatively, the tumor was purely extra-axial in the cranial nerve VII/VIII complex with an extension into the internal meatus. However, an intraoperative view of the tumor was different from classical acoustic neuronoma; therefore, a frozen section examination was performed, which revealed adenocarcinoma of unknown origin. Postoperative histopathological examination confirmed the diagnosis of adenocarcinoma, and postoperative systemic scans revealed a mass lesion on the right lung on a computed tomography scan. The patient was then referred to medical and radiation oncology clinics for further evaluation and treatment. Copyright © 2012 by Lippincott Williams & Wilkins.