Malignant Peripheral Nerve Sheath Tumor Arising After Superficial Neurofibroma Excision: A Rare Sporadic Case in a Patient Without Neurofibromatosis Type 1.

Malignant peripheral nerve sheath tumors (MPNSTs) are rare sarcomas that often arise in the setting of neurofibromatosis type 1 (NF1) or prior radiation exposure. Sporadic MPNSTs are significantly less common and rarely originate from superficial cutaneous neurofibromas. We present a unique case of MPNST arising at the site of a previously excised superficial neurofibroma in a patient without NF1. This case highlights the diagnostic complexity of MPNSTs arising in superficial cutaneous neurofibromas, requiring timely recognition given the tumor's aggressive behavior and poor prognosis. While degenerative changes within neurofibromas are typically benign, they may obscure early malignant transformation, complicating diagnosis. These findings underscore the need for continued surveillance of recurrent neurofibromas and further research into MPNST pathogenesis in non-NF1 populations.