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.

UNASSIGNED: Myoepithelial tumors are under-recognized neoplasms that could be difficult to identify due to their rarity and limited comprehension. Their diverse morphology, varied cytologic features and heterogenous immunohistochemical characteristics create a significant diagnostic challenge.
METHODS: We report the case of a 72-year-old-male patient who received conservative treatment during one year for a popliteal mass on the right knee that showed synovial hyperplasia (benign findings) at initial open tissue biopsy. New symptoms of popliteal area enlargement and discomfort required a second incisional biopsy to reach the diagnosis of a soft tissue myoepithelial tumor through tissue analysis and immunohistochemical staining.
UNASSIGNED: The myoepithelial tumors represent a medical dilemma due to their heterogenic features requiring high level of suspicion and adequate immunohistochemical markers for their diagnosis.
CONCLUSIONS: Orthopaedic surgeons should be aware of the atypical presentation of these rare neoplasms to provide an early diagnosis and adequate management.

Popliteal vein aneurysms (PVAs) are rare entities, with less than 300 hundred cases reported in the global literature. Despite their rarity, they have immense consequences, having the potential to lead to life-threatening conditions such as pulmonary embolisms and even death. Hence, it is vital for clinicians to be aware of this condition. In this paper, we report a case of PVA and its imaging features seen on the varying imaging modalities. Diagnosis often may not be straightforward as it can mimic other non-vascular or soft tissue masses, hence understanding and appreciating its specific imaging appearances is essential. Generally, PVAs are treated surgically with good outcomes with no reported mortality or recurrence of pulmonary embolism.

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.