Flow cytometric DNA analysis of benign hyperfunctioning parathyroid glands:: significant difference in the S phase fraction and proliferative index between adenomas and hyperplasias

Aims: Flow cytometric DNA analysis was performed to measure the DNA content of benign parathyroid tumours in patients with primary hyperparathyroidism. Methods: DNA analysis of paraffin-embedded parathyroid samples was performed on 51 parathyroid glands from 29 patients after parathyroidectomy. Histopathology showed parathyroid adenoma in 25 cases and hyperplasia in four patients. DNA ploidy status, DNA index (DI), percentage of cells in S phase and proliferative index (PI) were determined. Results: Normal cells from normal glands were all diploid. DNA cytometry showed 12 aneuploid and 13 diploid adenomas. There were 12 diploid and four aneuploid hyperplastic glands. Incidence of aneuploid DNA histograms did not show a statistically significant difference between adenomas and hyperplasias (P= 0.216). Mean S phase fraction was 3.45% in adenomas and 1.53% in hyperplasias (P= 0.015). Mean PI was 6.48% in adenomas and 2.78% in hyperplastic parathyroid glands. This difference was statistically significant (P = 0.006). Diploid cases had a mean PI of 4.78% and aneuploid glands a mean PI of 7.7% (P= 0.08). Aneuploid DNA content did not reveal statistically significant correlation with age, gender, pre-operative Ca, alkaline phosphatase, i-PTH levels, and tumour size. The mean S phase fraction and PI were 2.25% and 4.78% in diploid glands, and 4.5% and 7.7% in aneuploid cases. Conclusion: Aneuploid DNA content may be present in benign parathyroid diseases, but not in normal parathyroid glands. Aneuploid DNA histograms and higher PI occur more often in adenomas compared with hyperplasias, but the nuclear DNA analysis is unable to make a distinction between adenomas and hyperplasias.