Immunohistochemistry reflects their neurogenic origin, with the following immunoreactivity 8: The microscopic appearance of MPNSTs is heterogeneous, varying in cellularity and growth pattern, generally including tightly packed spindle cells arranged in either a herringbone or interwoven fasciculated pattern 8. It is common to identify areas of necrosis and hemorrhage 8. They are often large (>5 cm) at diagnosis, and may demonstrate local infiltration into surrounding tissues 8,9. The macroscopic appearance depends both on location and on whether or not the MPNST has arisen from an underlying pre-existing tumor. Most MPNSTs demonstrate inactivation of a number of genes: NF1, CDKN2A, and PRC2 8. Cranial nerves are rarely involved, and, on rare occasions they are, then the MPNST has usually arisen from an underlying schwannoma rather than a neurofibroma 8. brachial plexus/ sacral plexus), with the sciatic nerve the most commonly affected peripheral nerve 9. MPNSTs usually arise from a large nerve, and thus usually occur close to a plexus (e.g. These features are important in distinguishing MPNSTs from atypical neurofibromatous neoplasms of uncertain biologic potential (ANNUBP) 8. Rarely other neurogenic tumors (e.g schwannoma, ganglioneuroblastoma, ganglioneuroma, pheochromocytoma, perineurioma) 8Īlthough by definition, these are malignant lesions, the mitotic rate and presence of necrosis vary significantly between tumors and also within individual tumors 1. More often in plexiform neurofibromas than in cutaneous neurofibromas in NF1 Malignant peripheral nerve sheath tumors can arise in a number of different situations 8-10: These tumors are often fairly rapidly enlarging and clinical presentation varies depending on location with mass effect and pain often present 11. Risk factorsĭiagnostic criteria according to the WHO classification of soft tissue and bone tumors (5th edition) 9:Įssential: sarcoma arising from a nerve or pre-existing nerve sheath tumor or in an NF1 patient There is no recognized gender predilection. They typically present in young and middle-aged adults (20-50 years) 8,9. Malignant peripheral nerve sheath tumors are estimated to account for 3-5% of all soft-tissue sarcomas 9.
0 kommentar(er)
