gms | German Medical Science

Objective: Schwannomas mixed with islets of meningothelial cells are often seen in patients with neurofibromatosis type 2 (NF-2) (up to 21%). In contrast, "collision tumors, "which are defined by Frassanito et al., 2011 as “histologically distinct tumors arising at independent topographical sites, simultaneously growing, meeting together, and eventually intermingling,” are rare, even in patients with NF-2 and have primarily been described in single-case reports. We present the first series of 6 patients with seven meningioma-vestibular schwannoma collision tumors (MVSCT) to be treated in our department. Particular attention was paid to their clinical presentation, surgical treatment, early and late treatment outcomes, and survival rates.

Method: Patients who received surgical treatment for vestibular schwannomas (VSs) and meningiomas from January 2003 to July 2015 were identified by a computer search of their files from the Department of Neurosurgery, Tübingen. In 939 VS resections, 7 MVSCTs in patients with NF-2 were surgically treated. Clinical data were obtained from surgical pathology reports and surgical reports. Patients were considered to have NF-2 if the surgical pathology report indicated the presence of NF according to the Manchester criteria. The mean age of patients was 32 ± 8.2 years (range, 23-47 years). Two were male and four were female. Patients were evaluated for pre- and postoperative facial nerve function, pre- and postoperative cochlear function, complications, extent of tumor resection, and survival rate by reviewing surgical reports, patient documents and neuroradiological data.

Results: In 43% of MVSCT cases, complete or nearly complete tumor resection was achieved. In 71% of the cases, no facial palsy was present during a long-term follow-up. Facial nerve reanimation using an end-to-end interposed sural nerve graft was indicated in one case because of infiltration of the facial nerve by the VS. In 71% of the cases, some hearing loss was present preoperatively. Pre- and postoperative hearing impairment was experienced by 29% of the cases. In addition, it was noted that the mortality rate was 0%.

Conclusions: The outcome of the surgical removal of MVSCT in patients with NF-2 is less favorable than that of the surgical removal of VS in NF-2 without meningioma. One explanation for this result may be that all NF-2 patients were in the advanced stage of the disease. To the best our knowledge, this is the first study to report on the surgical treatment of MVSCT.