Surgical management of multiple schwannomas scattered on a single peripheral nerve

Background: Schwannoma is a common benign tumor. Most schwannomas are sporadic, but approximately 5% of schwannomas are multifocal. Schwannomas are sometimes present in a skip-like pattern on a single continuous peripheral nerve (Multiple schwannomas scattered on a single peripheral nerve: MSSPN). In this study, we present the clinical characteristics of MSSPN in the limbs and propose a treatment strategy based on treatment outcomes. Methods: The medical records of 918 patients diagnosed with schwannoma in the limbs were retrospectively reviewed. Among these cases, multiple schwannomas occurring in a single peripheral nerve and spaced more than 1 cm apart were defined as MSSPN. We investigated the clinical characteristics and surgical outcomes. Results: Seven patients with MSSPN in the limbs were identified, which represented 0.8% of all cases. There were six females and one male, and the mean age was 50 years. The location of MSSPN was the upper limbs in two cases and the lower limbs in five cases. After surgery, among the five cases in which all tumors were enucleated, neurological symptoms worsened in 4 cases, all of which involved deep nerve tumors. The one case among these five cases in which neurological symptoms improved involved a superficial subcutaneous tumor. Neurological symptoms improved in both of the two cases in which only the tumor causing the main complaint was enucleated; both cases involved deep nerve tumors. The average postoperative follow-up was 8 months, and no cases required reoperation or complained of recurrence. Conclusion: This is the first study to address the surgical strategies of multiple schwannomas occurring in a skip-like pattern on a single peripheral nerve. In surgery for MSSPN, selective enucleation of only the most symptomatic tumors may be effective in preventing the worsening of symptoms after surgery.