Quantitative analysis of the Callender classification of uveal melanoma cells.

Six experienced ophthalmic pathologists independently classified 90 uveal melanoma cells according to the Callender classification. They frequently disagreed among themselves, but at least four of the six agreed on the classification of 77 cells. In an effort to delineate those cytologic features that are most useful in the application of Callender classification, 12 factors were evaluated for each of these cells. Multivariate analysis (MVA) proved that six factors (chromatin clumping, minimum nuclear diameter, nucleolar diameter, chromatin margination, maximum nuclear diameter, and abundant cytoplasm) were useful for determining the cell type selected by the majority of pathologists, although some cells could not be sharply classified. It was concluded that uveal melanoma cells occupy a continuous cytologic spectrum, from benign-appearing spindle A cells to very malignant-appearing epithelioid cells.