Malignant Peripheral Nerve Sheath Tumors

 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 Spain identified 32 cases of cranial MPNST including our case. The age ranged from 5 to 75 years old with most patients being in the 5th and 6th decade. Male to female ratio is 2.5:1. Most cases are developed sporadically (50%), 31% arise from a malignant transformation of schwannoma and 19% from a neurofibroma. Imaging findings were not specific. The cranial nerve VIII is the most involved (15/32), followed by the Vth (10/32) and the VIIth (5/32). 4 cases had neurofibromatosis type 1 and 2 had neurofibromatosis type 2.