The adenomas which express more than one hormone (plurihormonal adenomas) seem to have a higher PCNA indices than monohormonal ones; the difference was significant in the case of mono- and plurihormonal prolactinomas.
In particular, 14 out of 55 adenomas (25%), independent of histological type, degree of dysplasia, location and size, showed a DNA-aneuploid content, trisomies and tetrasomies of chromosome 11 and high PCNA index.
PCNA positivity gradually increased in the sequence from HP to AC and were significantly higher in AC compared to HP (90% vs 44%; p = 0.00007). p53 positive cells were found in 67% of AC while only occasionally in other groups (HP vs AC: p = 0.0002, AD (low dysplasia) vs AC: p = 0.001; AD (moderate dysplasia) vs AC: p = 0.001).
Expression of p53 and PCNA were detected by immunocytochemistry in paraffin-embedded sections of infiltrating duct carcinoma and control breast tissue (normal tissue and adenoma).
The carcinomas had a higher proliferation rate than the adenomas when assessed either by SPF size (median 9.9 per cent vs. 2.9 per cent, P = 0.0003) or by PCNA staining intensity (P < 0.0001).