Germinoma in the Internal Auditory Canal Mimicking a Vestibular Schwannoma

The appearance of a primary germinoma in the central nervous system but not on or near the midline or within the brain is exceptional. It may occur at any age; however, it is rare in patients over 50 years old. Only a handful of cases of germinomas located in the cerebellopontine angle were presented, but to our knowledge, there has been no description of an isolated germinoma in the internal auditory canal. We report a case of germinoma in the internal auditory canal in a 51-year-old man simulating the clinical and radiological characteristics of a vestibular schwannoma. 1. Introduction Extragonadal germ cell tumors located in the brain are rare and are most commonly found in the pineal and suprasellar region. Germinoma is the most frequent intracranial one. It has a good prognosis and response to treatment and a high incidence among the Chinese and Japanese population [1]. The combined incidence of central nervous system germ cell tumors in males of all ages was 3.7 times higher than in females [2]. The peak incidence of intracranial germ cell primary tumors is at puberty. Clinical signs and symptoms of intracranial germinomas include visual disturbances, delayed sexual maturity, diabetes insipidus, and growth retardation [3]. The diagnostic confirmation requires histopathological studies that usually show epithelial tumor cells with pale eosinophilic cytoplasm and large round nuclei with evident nucleoli, expressing variable and organized mitotic activity sheets, lobes, nodules, and cords separated by thin fibrous and vascular septa, with small lymphoid cells with a perivascular organization [1]. We describe a case of a germinoma in a male without any risk factor, located in a place where it has never been previously reported: the internal auditory canal (IAC). The patient had an unusual age for the appearance of a primary germinoma (51 years old). We observed a tumor that both clinically and radiologically mimicked a vestibular schwannoma. 2. Case Report The patient is a 51-year-old man with right facial weakness of three weeks of evolution, including the inability to close the right eye (House-Brackmann grade 5/6 right facial weakness), bad response to oral corticoids, and deviation of the mouth on the same side. The patient did not present hearing loss, tinnitus, or ear fullness. The pure tone audiometry demonstrated a mild bilateral sensorineural hearing loss, predominantly in high frequency tones. The tympanogram showed type A curves without ipsi- and contralateral blink reflex in the right ear. Otoacoustic emissions were absent in both ears.