The use of flow cytometry in the study of parathyroid hyperplasia and adenomas

To discriminate benign from malignant parathyroid glands lesions is often difficult, because the morphologic features lack absolute diagnostic value. The differential diagnosis between chief cell hyperplasia and parathyroid adenoma is frequently based on physical features such as increased gland weight and number of enlarged glands. A carcinoma is identified by the evidence of local invasion, metastases or recurrence. Nevertheless the lesions classified as benign for lack of histologic features of aggressiveness can show nuclear atypia, increased mitotic figures and broad fibrous bands. Since DNA aneuploidy is present in a great number of human neoplasms and DNA aneuploidy has been suggest to be a marker of malignancy, flow cytometric assessment of ploidy appeared a possible method for rapid and objective distinction between benign and malignant lesions. Flow cytometric DNA content was evaluated on 113 parathyroid glands: the parathyroids were resected from 26 patients with hyperparathyroidism and from 17 patients with adenoma. The analysis was performed on paraffin-embedded specimens according to Hedley with minor modifications. Interpretable histograms were obtained for 103 parathyroids gland (mean CV = 5.3). Aneuploidy was detected in 22.5% of glands; in 12 instances of parathyroid hyperplasia the glands of the same patient showed different DNA Indexes. Cytometric results and morphological features do not correlate as far as aneuploidy and cellular atypia are involved. Although our results fail to show any correlation between morphology of parathyroid cells and DNA content, and abnormal DNA content suggests a careful follow up of these patients.