Ki-67 labeling index as a marker of malignancy in ocular surface neoplasms

To evaluate the relationships among histopathological type, clinical malignant grade, and Ki-67 labeling index (LI) in sebaceous gland carcinoma (SGC), conjunctival squamous cell carcinoma (SCC), and conjunctival intraepithelial neoplasia (CIN), with pterygium and normal conjunctiva as controls.

This retrospective study was conducted at the Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan. We used tissue specimens obtained from 20 patients (four SGC, four SCC, four CIN, four pterygium, and four normal conjunctiva). Ki-67 immunohistochemical analysis was performed in all 20 cases.

The Ki-67 labeling index (LI) was 46.1 +/- 3.0% (average +/- SD) in SGC, 28.4 +/- 4.5% in SCC, 20.0 +/- 7.2% in CIN, 9.0 +/- 2.2% in pterygium, and 6.8 +/- 2.3% in normal conjunctiva. Ki-67 LI was significantly (Mann-Whitney U test, P < 0.05) higher in SGC than in SCC, and higher, but not significantly, in SCC than in CIN. Ki-67 LI was significantly (P < 0.05) higher in SCC and CIN than in pterygium.

These results suggest that Ki-67 LI may be a sensitive marker for ocular malignant tumor grading.