IMMUNOHISTOCHEMICAL FEATURES OF MALIGNANT AND MULTIFOCAL PARATHYROID PATHOLOGIES Romans.Uljanovs@rsu.lv

PW06-10

IMMUNOHISTOCHEMICAL FEATURES OF MALIGNANT AND MULTIFOCAL PARATHYROID PATHOLOGIES

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Latvia

Oral or Poster

Primary hyperparathyroidism(PHP), caused by adenoma, multiglandular parathyroid disease(MPD) or carcinoma, represents the third most frequent endocrine disorder. Surgery is the mainstay of the treatment for PHP. Although the diagnostics of PHP is largely based on laboratory and radiological investigations, pathological assessment of surgically removed glands can verify the diagnosis or reach it in difficult and/or recurrent cases.

Proliferation activity by Ki-67, expression of parafibromin and proteins involved in cell cycle regulation (p21, p27, cyclin D1), and apoptosis (Bcl-2) was detected by immunohistochemistry and quantified by digital morphometry in 102 adenomas, 27 cases of MPD, 5 carcinomas and 45 normal glands. Statistic analysis included descriptive methods, Kruskal-Wallis and Mann-Whitney tests.

There were statistically significant differences between the studied groups, regarding the expression of parafibromin(p<0.001), Ki-67(p<0.001), p21(p<0.001), p27(p=0.01) and cyclin D1(p=0.002). Parathyroid carcinomas featured the highest proliferation fraction(5.8%), while in benign parathyroid pathology (BPP) the mean Ki-67 did not exceed 2%. The highest levels of p21 were observed in MPD(15.7%). Cyclin D1 was upregulated in MPD(24.8%) and carcinoma(31.5%). Only carcinomas showed loss of p27(59.0%, in contrast to >90% in BPP). Loss of BCL2 was notable in carcinoma(28.2%, compared with >60% in BPP). Loss of parafibromin was observed in all carcinomas, contrasting with adenomas(0%).

Parathyroid carcinoma was characterised by loss of parafibromin, elevated proliferation fraction, as well as loss of p27 and Bcl-2. In benign parathyroid disease, multifocality was associated with elevated p21 and cyclin D1 levels. Thus, immunohistochemistry may help to guide decision making in parathyroid surgery