Extraordinary Tumor Growth Rates in Bilateral Meningioma-Vestibular Schwannoma Collision Tumors in a Patient with Neurofibromatosis Type 2: Case Report and Literature Review

Abstract Collision tumors seem to be an extraordinary pathology with unusual features. We sought to report the management of very fast-growing bilateral meningioma-vestibular schwannoma collision tumors in a patient with neurofibromatosis type 2. Both meningiomas and both vestibular schwannoma, when analyzed by volumetry, showed a very rapid growth rate (0.476–0.833 cm3 per month) in comparison with two meningiomas of other locations (0.132–0.233 cm3 per month). To the best of our knowledge, the growth rates of both vestibular schwannomas in the present case are the fastest that have been described in literature for a vestibular schwannoma so far.