This article presents a case report of a 45-year-old male with neurofibromatosis type I (NF1) who developed a high-grade malignant peripheral nerve sheath tumor (MPNST) originating from a neurofibroma within the common peroneal nerve over popliteal fossa. MPNSTs are aggressive tumors associated with NF1, causing significant mortality. The patient underwent tumor resection surgery and received postoperative radiation therapy. Follow-up examinations showed no impairment of motor function and no tumor recurrence after regular MRI evaluation for four years. This article explores the challenges of distinguishing benign neurofibromas from malignant MPNST via MRI image and biopsy, and achieving a balance between tumor excision and preserving nerve functionality during surgical treatment. However, caution is warranted due to the risk of recurrence.

We describe a case of a 69-year-old male with a right-sided popliteal mass following a motor vehicle accident 15 years ago. The mass was indeterminate via multiple modalities (magnetic resonance imaging, digital subtraction angiography, and vascular ultrasound) with biopsy requested prior to surgical removal to determine the appropriate surgical team - vascular versus sarcoma oncologic surgery. Contrast ultrasound was utilized to determine if biopsy was indicated and if so, to determine the most appropriate target. Contrast ultrasound showed no areas of enhancement, therefore biopsy was not performed and the patient safely proceeded to vascular surgery. Pathology confirmed the mass to be a thrombosed pseudoaneurysm of the popliteal artery. We present the benefits of using contrast ultrasound in the work up and diagnosis of a popliteal neoplasm versus suspected vascular complication.