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 cm 3 per month) in comparison with two meningiomas of other locations (0.132–0.233 cm 3 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.