KI-67 Immunopositivity in Choroidal and Ciliary Body Melanoma with Respect to Nucleolar Diameter and Other Prognostic Factors

Abstract

Purpose: To study the association of cell proliferation in uveal melanoma with the mean of the 10 largest nucleoli (MLN), microvascular prognostic factors, and survival. Methods: Population-based, retrospective cohort study of 167 choroidal and ciliary body melanomas enucleated from 1972 to 1981. Mouse monoclonal antibody Ki-67 (clone 7B11) was used to identify proliferating cells. MLN was measured from silver stained slides. Kaplan-Meier and Cox regression analysis were performed. Results: The median number of Ki-67 immunopositive cells was 8 per tumor cross-section (range, 0–272) corresponding to a median of 0.30 cells/mm². The percentage of immunopositive cells was 0.02% of all cells (range, 0–3.2). Tumors with epithelioid cells tended to have a higher percentage of immunopositive cells (p = 0.089). Ki-67 immunoreactivity, MLN, and presence of extravascular loops and networks were independent predictors of melanoma-related mortality, whereas Ki-67 immunoreactivity was not an independent predictor of mortality when presence of epithelioid cells was in the model. Conclusions: Taken together with previous data, the results of this population-based study support the theory that high cell proliferation index is associated with presence of epithelioid cells and that presence of a high cell proliferation index is associated with a higher risk of metastatic death independent of MLN, microvascular density, and presence extravascular loops and networks.

KEYWORDS:

• cell proliferation
• Ki-67 antigen
• microvascular density
• mortality
• nucleolar morphometry
• uveal melanoma
• vasculogenic mimicry