ACTA ENDOCRINOLOGICA (BUC)

Objective. Parathyroid gland hyperplasia is diffuse or nodular in secondary hyperparathyroidism (sHPT) in patients with renal failure. Whether the nodular growth starts from the beginning or is the transformation of a diffusely-growing gland into nodular hyperplasia in parallel\r\nwith increases in the severity of the disease is unknown. The disease might be unresponsive to medical treatment when\r\nnodular hyperplasia develops. This study aims to differentiate the characteristics of the parathyroid glands with and without nodular hyperplasia in sHPT, and to\r\ninvestigate if there is any similarity between the nodular hyperplastic glands of sHPT and the parathyroid adenomas of primary hyperparathyroidism.\r\nMaterials and Methods. Hyperplasia types (nodular or diffuse) and parathyroid cell types, and the expression of\r\nproliferating cell nuclear antigen (PCNA) and Ki-67 in parathyroid tissue were investigated histopathologically and\r\nimmunohistochemically in 94 parathyroid glands of 42 patients with hyperparathyroidism.\r\nResults and Discussion. 63 glands showed nodular hyperplasia and 16 diffuse hyperplasia in sHPT. Chief cells predominated across the whole series. Vacuolated chief cells most frequently accompanied chief cells in both nodular\r\nhyperplasia (28.6%) and adenomas (53%). The median ratio of PCNA LI (labelling index) was 30/10? (min: 4-max: 720) cells in nodular hyperplasia, 16/10? (min: 2-max: 180) cells in diffuse hyperplasia and 30/10? (min: 10-max: 707) cells in adenomas (p>0.05). The highest PCNA LI according to all the cell types in the series was in chief cell and vacuolated chief cell combinations (53/10?, p=0.04). These findings suggest that parathyroid adenoma and nodular hyperplasia have histopathologically- and immunohistochemically - simil ar characteristics suggesting that both have aggressive cell proliferation.