Multifocal malignant peripheral nerve sheath tumor in patients with neurofibromatosis type I: Report of two cases and review of literature.

Malignant peripheral nerve sheath tumors (MPNSTs) are one of the rarest soft-tissue sarcomas with a prevalence of 0.001% in the general population. It is closely associated with a unique neurocutaneous stigmata under the spectrum of the dermatological manifestations of neurofibromatosis type 1 (NF1). Almost 81% of MPNST arises from a precursor neuroma, and multifocality of these lesions is extremely rare, making up to 0.001% of cases. Moreover, spinal cases are extremely uncommon with only four cases reported internationally. Here, we present the fifth and sixth spinal MPNST cases with a brief review of literature. We describe two unusual cases of multifocal MPNST in relation to NF1 occurring in the spinal cord. Both patients presented with local pain and myelopathic symptoms. The two patients underwent wide surgical resection, followed by neoadjuvant radiotherapy and reported immediate postoperative improvement of the presented complaint; however, one patient suffered from rapid recurrence and metastasis. Due to the scarcity of spinal cases related to MPNST, no clear guidelines regarding the management of these cases are set in the literature. Histopathological diagnosis remains as the most pivotal diagnostic tool as they can mimic other peripheral nerve sheath lesions, such as neuromas and schwannomas, in imaging. Cases that were managed by early surgical intervention in addition to neoadjuvant radiotherapy reported the best outcome. However, cases of MPNST in concomitance with NF1 were found to be resistant to both chemo and radiotherapy and have high recurrence rate.