Malignant peripheral nerve sheath tumor: pathology and genetics.

Malignant peripheral nerve sheath tumors are soft tissue neoplasms that show differentiation toward cells of the nerve sheath. They often arise from peripheral nerves or preexisting benign nerve sheath tumors and are generally high-grade neoplasms, which behave aggressively with high incidence of distant metastases. Malignant peripheral nerve sheath tumor can be histologically diverse and is difficult to diagnose because of its morphological overlap with a variety of other sarcomas and its lack of specific immunohistochemical markers or genetic profile. We review the pathology of malignant peripheral nerve sheath tumor, with reference to etiology, molecular genetics, and clinical factors.