Neoplasia USMLE Step 1 Practice Question
A 28-year-old man with neurofibromatosis type 1 presents with progressive back pain and dyspnea. Vital signs show BP 128/82, HR 92, RR 20, SpO2 94% on room air. MRI reveals a large posterior mediastinal mass with cystic and solid components. Biopsy demonstrates fascicles of malignant spindle cells with high mitotic activity and areas of necrosis. S100 protein is strongly positive. There is no evidence of metastatic disease on staging CT. What is the most likely diagnosis?
Answer choices
- AMalignant peripheral nerve sheath tumor (MPNST)Correct answer
- BBenign neurofibroma with reactive atypia
- CSynovial sarcoma of the mediastinum
- DGanglioneuroma with fibroblastic differentiation
- ESchwannoma with hemangiopericytoma pattern
- FLeiomyosarcoma of the mediastinal vessels
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