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

Background: It is widely accepted that histological diagnosis of parathyroi d tumors is established with great difficulty. Carcinomas cannot be reliabl y separated from adenomas by histology alone, In this study, immunohistoche mical staining for proliferating cell nuclear antigen (PCNA) and Ki-67 was determined in 10 cases of parathyroid carcinomas, labeling indices (LIs) we re calculated, and the results were correlated with the clinical outcomes. Methods: Ten cases of formalin-fixed, paraffin-embedded tissue with surgica lly resected parathyroid carcinoma were used. Immunohistochemical staining for PCNA and Ki-67 was performed and the LIs were calculated. We also exami ned whether LI could become a useful marker for parathyroid carcinomas. Results: Although nine patients with minimally invasive growth without recu rrence of the tumor showed a low LI for both markers, one patient with a wi dely invasive neoplasm, and who died, had a high LI. Conclusions: These results suggested that the LI of PCNA and Ki-67, in addi tion to the histological appearance, may be markers of the biological behav ior 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 w ith better defined histological criteria.