Benign schwannomas: pathologic basis for CT inhomogeneities.

Four cases of pathologically proven benign schwannoma were reviewed and the histology was compared with the CT appearance. Each tumor was of mixed CT attenuation, which has been thought to be an indication of malignancy. The areas of inhomogeneity on CT in these cases may relate pathologically to confluent areas of hypocellularity adjacent to densely cellular or collagenous regions, xanthomatous change, and/or regions of cystic degeneration. It is concluded that schwannomas may have areas of mixed attenuation on CT, that these areas can probably be explained by distinct findings on pathologic examination, and that inhomogeneity can represent benign or malignant disease.