HISTOLOGY AND NEURO-IMAGING IN CYSTIC ACOUSTIC NEUROMAS

Tumor configuration and attenuation on CT scan with contrast enhanceme nt or gadolinium-DTPA-enhanced MR depends upon tumor histology. Variou s elements are responsible for the density on CT or MR, e.g. blood ves sels, fatty tissue, connective tissue, calcium, necrotic tissue, hemor rhage and intra- or extratumoral cyst formation. In a series of 571 ac oustic neuromas we found 23 cystic tumors. The diagnosis was based on neuro-imaging examination, confirmed at surgery and finally verified h istologically. Eight tumors with small or large cysts were diagnozed b y CT or MR scan as intratumoral, and 15 with large cysts were diagnoze d as extratumoral. We found a good correlation between the histology o f cystic acoustic neuromas and the CT or MR scans. The tumors were pre dominantly hypodense, corresponding to the cystic areas, but also iso- or hyperdense areas were observed, corresponding to other tissue type s. Antoni type B tissue and xanthomatous areas were found in all 23 ca ses.