Mitotic Index and Immunohistochemical Expression of Ki-67 in Pleomorphic Adenoma of Salivary Glands

Abstract

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Background: Pleomorphic adenomas (PAs) are the most common type of salivary gland tumors (SGTs) which may undergo malignant transformation to Carcinoma ex PA (CaExPA). The purpose of this study was to determine mitotic index (MI) and expression of Ki-67 in Pleomorphic adenomas of salivary gland tumors.

Methodology: This study was carried out on sixty patients of pleomorphic adenoma. Slides with specimens were stained with Hematoxylin & Eosin to count Mitotic index. Labeling Index (LI) of Ki-67 was determined immunohistochemically. Mitotic figures (MF) were counted in 10 HPF selected in the proliferative area. MI was scored as 1 (0 to 4 MF per 10 HPF); 2 (5-9 MF per 10 HPF) and 3 (> 9 MF per 10 HPF). Immunoexpression of Ki-67 was scored as ‘0-negative’ when <5% of neoplastic cells stained, ‘1-weak positive’ when 5-19% of neoplastic cells were stained, ‘2-moderate positive’ when 20-49% of neoplastic cells were stained, and ‘3-strong positive’ when >50% of neoplastic cells were stained with Ki-67. Data was, entered in SPSS 21.

Results: Mean age was 38.7 ± 12.86 years. Out of 60 cases, 26 (43.33%) were of males while 34 (56.67%) were of females. Expression of Ki-67 was negative in 50% while remaining weak positive. Only score 01 of MI observed.

Conclusion:  Ki-67 is more sensitive marker than mitotic index in pleomorphic adenomas even in small sized tumors and it can help in detection of malignant transformation of PAs.

Keywords: Adenomas, Immunohistochemistry, Ki-67 Antigen, Parotid Neoplasms, Pleomorphic