MIB-1 PROLIFERATIVE INDEX IN PARATHYROID ADENOMA AND HYPERPLASIA

A retrospective study on 22 cases of parathyroid adenoma, 9 cases of p rimary parathyroid hyperplasia and 14 specimens of normal suppressed g landular tissue was undertaken to determine the usefulness of prolifer ative index (PI) for discriminating adenoma from hyperplasia, as an ad junct to the existing histological criteria. PI was determined by avid in-biotin-complex immunostaining after high temperature microwave anti gen retrieval in paraffin sections, using monoclonal MIB-1 antibody wh ich detects paraffin resistant analogue of cell cycle-associated Ki-67 antigen. PI expressed as percentage positive cell nuclei, was 1.36 +/ - 0.62 (range 0.04 - 2.72) in adenoma, 1.17 +/- 0.83 (0.02 - 1.98) in hyperplasia and 0.03 +/- 0.02 (0.00 - 0.06) in normal suppressed gland ular tissue. While the difference between normal suppressed glandular tissue and adenoma and hyperplasia was significant (P < 0.001), that b etween adenoma and hyperplasia was not. We conclude that although PI c ould distinguish between normal suppressed glandular tissue versus gla nds with primary hyperparathyroidism, it failed as an additional usefu l parameter for discriminating between adenoma and hyperplasia, both o f which have low but similar proliferative activity.