Gamma-enolase activity in choroidal melanoma.

Gamma-enolase is a glycolytic enzyme that is found in high concentration in neural and neuroendocrine tissues. The enzyme has been considered clinically useful as a tumor marker in the evaluation of small-cell undifferentiated malignancies. A preliminary report suggested that gamma-enolase activity may be used in the assessment of the malignant potential of choroidal melanoma. To test this hypothesis and document the distribution of gamma-enolase in the eye, we studied the immunohistochemical activity of gamma-enolase in six eyes from persons with choroidal melanoma. Although no correlation could be found with gamma-enolase activity and tumor size or tumor cell type, the distribution of gamma-enolase in normal retina and optic nerve was described. The areas of greatest immunohistochemical reactivity were the perikaryon of ganglion cells, inner and outer plexiform layers, and the nerve axons of the nerve fiber layer and optic nerve. Gamma-enolase may be a potentially useful marker of retinal and optic nerve glycolysis, and of neuronal function.