A Bilateral Vestibular Schwannoma is Not Always Related to Neurofibromatosis Type 2.

Bilateral vestibular schwannomas are commonly diagnosed in patients affected by neurofibromatosis type 2, a genetic disease caused by a heterozygous mutation in the gene region encoding neurofibromin-2. Sporadic bilateral vestibular schwannomas are very rare entities affecting almost exclusively elderly people. We present the case of a senior woman who was followed up with the "wait-and-scan" strategy for a unilateral vestibular schwannoma that later developed as a contralateral tumor, compatible with vestibular schwannoma, raising questions about its nature and risk of having been transmitted in offspring. Genetic testing excluded mutations of the neurofibromatosis type 2 gene. The presence of bilateral vestibular schwannomas is often considered pathognomonic of neurofibromatosis type 2, but the estimated probability of sporadic bilateral tumors in the absence of other neurofibromatosis type 2 features is 50% over 70 years of age. Therefore, the NF2 gene assessment is in any case recommended in these patients not only for an evaluation of the risk of being transmitted. The treatment strategy should be carefully personalized for each patient, considering the size of the tumors, symptoms, and hearing function together with the patient's age.