Malignant peripheral nerve sheath tumors arising from schwannomas: case series and literature review

A malignant peripheral nerve sheath tumor (MPNST) arising from a schwannoma is extremely rare, with limited literature on its clinicopathologic features. Here, we present a case series and literature review on patients with MPNSTs arising from schwannomas. We performed a retrospective review of patients from our institution’s records to identify those with MPNSTs arising from schwannomas. We conducted a search for additional cases from the literature utilizing PubMed. 20 patients (including 2 at our institution and 18 from 16 prior publications) were identified. The patients aged 22–93 (mean 52) years, and 63% were females. Histologically, while most MPNSTs arising from schwannomas were of epithelioid‐type, 7 tumors (including 2 at our institution) were of conventional spindle‐cell type. All 20 patients underwent surgical excision, while a subset received additional radiotherapy and/or chemotherapy. In 17 patients with available follow‐up, the overall survival was 2–72 (median 12) months. MPNSTs rarely arise from schwannomas and should be considered in patients with a clinical diagnosis of schwannoma, however, with atypical radiologic or clinical features. MPNSTs arising from schwannomas can show epithelioid or spindle‐cell histology and harbor an aggressive course, even with surgical excision and adjuvant treatment.