Computed Tomography of Extracranial Nerve Sheath Tumors with Pathological Correlation

Abstract

Computed tomography was obtained in 15 patients with extracranial nerve sheath tumors, including 8 with neurofibromatosis. The studies included 2 schwannomas, 6 neurofibromas, 4 plexiform neurofibromas and 3 neurofibrosarcomas. Lesions with attenuation values exceeding 30 Hounsfield units had dense bands of collagen in resected specimens. Eleven of the lesions had attenuation values which were significantly lower than muscle. Histological examination of hypodense lesions revealed 5 factors contributing to reduced attenuation values: a population of lipid-rich Schwann cells; the presence of adipocytes (transformed fibroblasts) in neurofibromas; entrapment of perineural adipose tissue by plexiform neurofibromas; a coalescence of interstitial fluid to form cystic spaces in Schwannoma with Antoni B tissue; and cystic degeneration secondary to infarction or necrosis within neurofibromas and neurofibrosarcomas.