Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas on peripheral nerves or nerve sheath. These MPNSTs can occur on any cell type and differs from one to other. A sarcoma is regarded as MPNST only when it is raised on the peripheral nerve or it exists on neurofibroma. MPNSTs usually present as an enlarging palpable mass. Pain is a variable complaint. Rapid enlargement occurs more often in the setting of NF1 and should raise concern for malignant degeneration of a neurofibroma.
In Brazil Oral peripheral nerve sheath tumors represented 35 (0.2%) of 21,476 specimens biopsied from 1966 to 2006 in the Oral Pathology Service, FO-UFMG. The cases diagnosed included 15 (42.9%) traumatic neuromas, 10 (28.6%) solitary neurofibromas, 2 (5.6%) neurofibromas associated with neurofibromatosis type I, 4 (11.4%) neurilemmomas, 1 (2.9%) PEN, and 3 (8.6%) MPNSTs.