Malignant Peripheral Nerve Sheath
Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas which originate from peripheral nerves or from cells associated with the nerve sheath, such as Schwann cells, perineural cells, or fibroblasts.
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Malignant Peripheral Nerve Sheath Tumors (MPNST) are a type of malignant soft tissue sarcoma involving the nerves. The term MPNST replaces a number of previously used names including malignant schwannoma, neurofibrosarcoma, and neurogenic sarcoma.
The words 'malignant schwannoma' are also used to note that the tumor cells resemble Schwann cells. These tumors may arise within a preexisting benign schwannoma, especially in neurofibromatosis. This changing from benign to malignant is called malignant transformation. Ten percent of all soft tissue sarcomas are malignant schwannomas, and half of them are related to neurofibromatosis (NF or von Recklinghausen's disease). They occur more often in men who present with a large mass causing pain which radiates or travels down the extremity.
Examination of the tumor usually shows the nerve entering at the top of the tumor and existing at the bottom of the tumor. The tumor cells are shaped like commas and collect in a wavy, picket-fence type pattern. Wide excision with limb-sparing procedures or amputation are treatment options for malignant schwannomas, along with radiation and chemotherapy. Patients with tumors larger than 8 centimeters will undergo the MAID protocol, which can be seen on the liposarcoma page.