A 26-year-old man with neurofibromatosis type 1 (NF1) presented with a giant malignant schwannoma of the sciatic nerve. The differential diagnosis of malignant peripheral nerve sheath tumor (MPNST) was based on clinical, radiological, and histological evidence. The tumor apparently originated in a spinal plexiform neurofibroma. The lesion was resected totally without neural damage to the sciati...