Proliferating cell nuclear antigen (PCNA) in atypical and malignant meningiomas

Because it is not easy to determine the tumor status o f meningiomas by current diagnostic procedures, we investigated these tumors immunohistochemically using the monoclonal antibody PC 10. This antibody recognizes a fixation- and processing-resistant epitope o f the proliferating cell nuclear antigen (PCNA), which is a 36-KD nuclear antigen associated with the cell cycle. We studied paraffin-embedded and f ormalin-fixed tissue specimens o f a group o f 21 atypicallmalignant meningiomas together with 18 benign meningiomas. PCNA staining results were compared with -the mean number o f silver-stained nucleolar organizer region-associated proteins (AgNORs), tumor grading, and mitotic indices o f these tumors. The percentage o f PCNA-positive cells was found to range between 0.1 and 40%, irrespective o f the tumor grade. When all tumors were collectively considered, no positive correlation was found between PCNA scores and histologic grading and only a weak one between PCNA score and mitotic index. A higher correlation was seen between AgNOR counts and tumor grading. Our results suggest that PCNA labeling and histologic grading seem to be independent parameters. The correlations found between AgNOR counts and tumor grading should be substantiated in further series.