Implications of DNA characterization of human acoustic neuromas.

Based on in vitro detection of cell-mediated immunity against human acoustic neuroma extract, a malignant potential of acoustic neuromas could be surmised, as malignant DNA patterns have been demonstrated in benign pituitary tumours. Flow-cytofluorometric characterization of the DNA content in 10 human acoustic neuromas, however, only revealed diploid cell lines and normal distributions of cells in different cell cycle phases. All acoustic neuromas were histopathology benign. The percentage of cells in S-phase (range: 1.8-8.3%, median: 3.6%) reflected a slow growth rate correlated neither to age, size of tumour, nor length of case history at time of surgery. These findings may in part be due to the analytical variation in the determinations of the S-phases. The investigation has not offered any explanation for the observed cell-mediated immunity against acoustic neuromas, and confirms that acoustic neuromas are benign tuours.