Metastatic Malignant Peripheral Nerve Sheath Tumor (MPNST) in Neurofibromatosis Type 1: Challenges in Diagnosis and Management

Malignant peripheral nerve sheath tumors (MPNSTs) are growths that arise in conjunction with a peripheral nerve and are believed to originate from neural crest cells. These tumors can arise sporadically but are often associated with the cancer-predisposing genetic condition, neurofibromatosis type 1 (NF-1). The clinical presentation of an enlarging mass, pain, paresthesias, and neurologic deficits can mirror that of other soft tissue sarcomas. Thus, clinical suspicion should remain high for an MPNST when this aggregation of symptoms arises, particularly in those with a genetic proclivity. We report the case of metastatic MPNST in a 44-year-old female with a long history of NF-1. She was first seen for evaluation of progressive forearm and hand weakness associated with numbness and paresthesias in her second through fourth digits which prompted a need for an MRI. A forearm mass was discovered, and she underwent surgical intervention which revealed an MPSNT with positive margins. The patient completed radiation therapy for this lesion, but ultimately her forearm lesion recurred and progressed with metastasis to the lungs. Local recurrence was managed with a trans-humeral amputation and her systemic involvement necessitated chemotherapy. She was ultimately enrolled in a clinical trial for adult patients with recurrent advanced solid tumors. Given the potentially fatal course of NF-1-associated MPNSTs, clinical suspicion should remain high and early diagnosis and intervention with regular clinical surveillance are of utmost importance in this patient population.