Malignant Peripheral Nerve Sheath Tumor of the Neck: Transformation From a Recurrent Neurofibroma in a Patient Without Neurofibromatosis

Malignant peripheral nerve sheath tumor (MPNST) is a rare tumor that is one of the most aggressive malignant lesions in the head and neck area. The majority of MPNSTs arise de novo or from malignant transformation of pre-existing neurofibromas, particularly in individuals with neurofibroma-tosis type 1 (NF1). However, solitary neurofibromas without an association with NF1 seldom recur after excision and rarely develop malignant changes. We present a 70-year-old man with a recurrent neurofibroma of the right side of the neck which transformed to low-grade MPNST after multiple excisions. The patient had no cutaneous features or family history consistent with NF1. Progression from a recurrent sporadic neurofibroma to malignancy is an extremely rare event and we found only two case reports in the literature. Any recurrent mass at the site of an excised neurofibroma or a rapidly enlarging, painful swelling of antecedent lesions should prompt consideration of MPNST.