A comparative study of p53 immunoexpression in parathyroid hyperplasias secondary to uremia, primary hyperplasias, adenomas and carcinomas.

OBJECTIVE: To investigate immunoexpression of p53 in parathyroid tumors and hyperplasias and correlate it with the histopathological diagnosis and severity of hyperparathyroidism.
DESIGN: A total of 102 parathyroid tissues from archival paraffin-embedded specimens or obtained at surgery between 1988 and 1997 from 65 consecutive individuals with hyperparathyroidism were studied.
METHODS: p53 immunoexpression, gland mass, preoperative serum calcium and intact parathyroid hormone (PTH) were analyzed; 14 normal parathyroid glands were used as controls.
RESULTS: The histopathological findings were: adenomas (n = 28), primary hyperplasias (n = 12), secondary nodular and diffuse hyperplasias (patients with uremia, n = 57), carcinomas (n = 4) and carcinomatous metastatic tissue (n = 1). Nuclear p53 was detected in 36% of the adenomas, 42% of the primary hyperplastic glands, 72% of the diffuse hyperplasias, 44% of nodular hyperplasias and 40% of the carcinomatous tissues, and was absent from normal glands. p53 expression was significantly more frequent in diffuse hyperplasias than in adenomas (P = 0.037). Serum ionized calcium tended to be higher in p53-positive glands in all histopathological groups; however, the difference was only significant in nodular hyperplasias (P = 0.018). The same trend was observed for serum intact PTH levels of adenomas and nodular hyperplastic glands. Gland mass was not significantly different according to p53 staining.
CONCLUSIONS: p53 immunoexpression was not useful in differentiating between the histopathological parathyroid subgroups. p53 immunodetection was particularly frequent in secondary hyperplastic glands of uremic patients. Our study suggests that p53, whether wild-type or mutant, is regulated in parathyroid tumors and hyperplasias. Changes in wild-type p53 may be part of a cellular response to a hyperproliferative condition.