Malignant peripheral nerve sheath tumor (MPNST), also known as Neurosarcoma, is a rare and aggressive type of cancer that originates in the cells surrounding the peripheral nerves. These tumors can occur anywhere in the body but are commonly found in the extremities, head, and neck regions. MPNSTs are often associated with neurofibromatosis type 1 (NF1), a genetic disorder that causes tumors to form on nerve tissue.