P53 as a marker of differentiation between hyperplastic and adenomatous parathyroids.

Primary hyperparathyroidism is the clinical result of parathyroid adenoma or hyperplasia, rarely of carcinoma. Clinical, serologic, and radiologic data are unable to discriminate a single parathyroid adenoma from an enlarged hyperplastic gland. Morphologic features also overlap in adenoma and small hyperplastic gland. Studying immunohistochemical expression of fatty acid synthase (FAS), p53, Ki67 and bcl-2, we found that among 21 adenomas 19 (90.5%) were positive for FAS, 12 (57.2%) for Ki67, 11 (52.4%) for p53, and 16 (76.2%) for bcl-2; among 12 hyperplasias, 12 (100%) were positive for FAS, 6 (50%) for KI67, 8 (66.7%) for p53, and 8 (66.7%) for bcl-2. Statistical analysis showed that FAS was associated with parathormone (PTH) (P =.001), Ki67 (P =.01), and p53 (P =.01). Moreover, FAS was associated with hyperplastic (P =.0001) and adenomatous glands (P =.0001). Ki67 was associated with both adenomatous (P =.02) and hyperplastic glands (P =.005). P53 protein were associated only with hyperplastic glands (P =.01). The different occurrence of p53 in parathyroids adenoma and hyperplasia may enable a different management and follow-up of the patients with primary hyperparathyroidism, stratifing them into two groups. The first, with a "false" adenoma having a high risk of relapse, may necessitate exams like serum calcium levels, PTH concentrations, urinary calcium levels for 24 hours, kidney functional tests, and radiology and ultrasound every 3 to 6 months, whereas the second with "true" adenoma, at low risk of relapse, may be checked less frequently with serum calcium levels and PTH concentrations.