Flow cytometric DNA analysis of normal and pathologic parathyroid glands

Assessment of cellular DNA content and cell cycle analysis by flow cytometry has been useful in predicting patient survival and the malignant potential of many neoplasms. In this study, we analyzed the DNA content and cell cycle distribution of 12 parathyroid adenomas, 15 carcinomas, 5 secondary hyperplasias, and 14 normal parathyroid glands. Appropriate areas demonstrating the pathologic changes were dissociated from paraffin-embedded, formaldehyde-fixed tissue for this purpose. All the cells from normal glands were diploid with mean and median S-phase fractions of 1.2% (range, 0.3-2.7%). Of the 18 glands from five patients with secondary hyperplasia, 4 (22%) had some cells which were aneuploid (from three patients), and 14 (78%) had only cells with a diploid DNA content. Mean and median S-phase fractions were 0.8% (range, 0.3-1.5%). One (8%) of the adenomas was tetraploid, 3 (25%) were aneuploid, and 8 (67%) were diploid. The mean S-phase fraction was 1.5% (range, 0.3-3.8%). Four (27%) of the carcinomas had tetraploid cells, 6 (40%) had aneuploid cells, and 5 (33%) had only diploid cells. Carcinomas had a mean S-phase fraction of 6.0% (median, 5.3%; range, 1.4-14.1%). This study indicates that DNA aneuploidy or tetraploidy may be present in many abnormal parathyroid entities, but not in normal parathyroids. Proliferative activity when considered with the DNA index may be a helpful adjunct in separating carcinomas from adenomas or hyperplasias.