Tumors of Peripheral Nerves
Of the cells that constitute peripheral nerves, those that develop tumors are mostly Schwann cells. Infrequently, however, some tumors originate from peripheral nerve cells. Because Schwann cells differentiate in different ways, histological profiles of the tumors are also diverse. Benign tumors are often schwannomas, neurilemomas, or neurofibromas. The incidence of solitary schwannoma is relatively high, and it is often encountered clinically when lesions arising in the spinal cord are included. Neurofibroma is known to occur in association with von Recklinghausen’s disease, but its solitary occurrence is also not rare. Among malignant tumors, malignant schwannoma is well known, but malignant tumors that arise in the nerve sheath and are composed mainly of spindle cells have recently come to be collectively called malignant peripheral nerve sheath tumors (MPNST). The proportion of MPNST in all malignant tumors of soft tissue is not large. Slightly less than two-thirds of them are neurofibromas associated with von Recklinghausen’s disease, especially plexiform neurofibroma, that has become malignant. Benign and malignant Triton tumors, which show striated muscle formation, are considered to develop as a result of special differentiation of Schwann cells. Schwann cells may become epithelioid or melanin-producing, or they may form tumors resembling melanoma.
KeywordsPeripheral Nerve Schwann Cell Brachial Plexus High Signal Intensity Malignant Peripheral Nerve Sheath Tumor
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