Malignant Peripheral Nerve Sheath Tumor in Neurofibromatosis Type 1 Mimicking an Infected Wound: A Case Report

Abstract

Introduction: Malignant peripheral nerve sheath tumors (MPNSTs) are rare, aggressive soft-tissue sarcomas that may arise sporadically or in association with neurofibromatosis type 1 (NF1). NF1-associated MPNSTs are associated with substantial morbidity and mortality, particularly when diagnosis is delayed or metastatic disease is present. Rapid tumor growth, pain, neurological symptoms, or changes in pre-existing neurofibromas should raise clinical suspicion for malignant transformation.

Case Presentation: A 64-year-old woman with NF1 presented with a 5-month history of a progressively enlarging mass over the anterior aspect of the right knee and a 1-week history of fever and wound discharge. A 13 × 13 cm lobulated mass was identified clinically, along with multiple superficial cutaneous nodules consistent with NF1. She was initially treated for a presumed infected wound. Biopsy subsequently demonstrated a high-grade MPNST. Magnetic resonance imaging revealed a heterogeneous 7.4 × 11.8 × 13.2 cm mass with restricted diffusion and cystic components involving the anterior knee region. Staging investigations identified multiple bilateral pulmonary nodules and enlarged right inguinal lymph nodes suspicious for metastatic disease. The patient developed severe sepsis with uncontrolled local infection. Because of extensive involvement of critical structures and the inability to achieve adequate limb-sparing margins, above-knee amputation was performed. Histopathological examination confirmed a 13.5 cm high-grade MPNST with involvement of the deep and subcutaneous soft tissues and negative surgical margins. Anthracycline-based systemic chemotherapy was planned; however, the patient developed acute pulmonary edema and cardiac arrest five days after discharge and died.

Conclusion: This case illustrates the aggressive clinical course of NF1-associated MPNST and the diagnostic challenges that may arise when malignant transformation initially presents with infection-like features. Rapid enlargement of a mass in a patient with NF1, particularly when accompanied by ulceration, pain, or neurological symptoms, should prompt timely imaging and tissue diagnosis. Early recognition and multidisciplinary management are essential, although prognosis remains poor in patients with large, high-grade, or metastatic tumors.