[DNA analysis of meningiomas using paraffin-embedded surgical specimens in connection with clinical recurrence]

Meningioma includes some clinically malignant cases which grow multifocally or recur rapidly. To develop methodology to distinguish clinically malignant cases, we examined the nuclear DNA of meningiomas by flow cytometry using paraffin-embedded specimens. 52 surgical specimens were studied from 52 cases of meningioma. Among these cases, 3 multiple meningiomas that recurred multifocally within 3 years were included. Malignancy was assessed by the proliferative index (%S + %G2/M) and DNA ploidy of the specimens. Six cases were histologically malignant, while aneuploidy was observed in only 2 (33.3%). No significant correlation was observed when analyzing the 23.9% aneuploidy rate among benign cases. Moreover, three cases of clinically malignant meningiomas were all diploid. In contrast, the proliferative index of 19.82 +/- 9.45% among histologically malignant cases was significantly higher as compared to that for benign cases (11.50 +/- 5.49%). The proliferative index was 15% or more (average 22.02 +/- 6.01%) for patients with clinically malignant meningioma. This was considerably higher than the corresponding value for clinically benign meningiomas. Our analysis indicated that the assessment of benignancy or malignancy of meningioma on the basis of DNA ploidy alone is difficult. The proliferative index so obtained relates significantly to prognosis, apparently providing a useful prognostic assessment.