PCNA and Ki-67 as prognostic markers in human parathyroid carcinomas

Background: It is widely accepted that histological diagnosis of parathyroid tumors is established with great difficulty. Carcinomas cannot be reliably separated from adenomas by histology alone. In this study, immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and Ki-67 was determined in 10 cases of parathyroid carcinomas, labeling indices (LIs) were calculated, and the results were correlated with the clinical outcomes. Methods: Ten cases of formalin-fixed, paraffin-embedded tissue with surgically resected parathyroid carcinoma were used. Immunohistochemical staining for PCNA and Ki-67 was performed and the LIs were calculated. We also examined whether LI could become a useful marker for parathyroid carcinomas. Results: Although nine patients with minimally invasive growth without recurrence of the tumor showed a low LI for both markers, one patient with a widely invasive neoplasm, and who died, had a high LI. Conclusions: These results suggested that the LI of PCNA and Ki-67, in addition to the histological appearance, may be markers of the biological behavior of parathyroid carcinomas. However, this study was on a small scale, so it may be valuable to repeat these studies in a larger group of patients with better defined histological criteria.