Neuron-specific enolase expression and neuroendocrine differentiation in carcinomas of the breast.

The concentration of neuron-specific enolase (NSE, gamma-subunit of enolase) in tumor extracts of 25 nonargyrophilic and seven argyrophilic carcinomas of the female breast was measured by radioimmunoassay. The mean concentration of NSE in nonargyrophilic carcinomas was 89 ng/mg of protein, (range, 9 to 281 ng/mg), and the mean concentration of NSE in argyrophilic carcinomas was 153 ng/mg of protein (range, 4 to 420 ng/mg). All carcinomas, irrespective of the silver reaction, could be grouped in regular histopathologic terms. Neuron-specific enolase immunoreactivity in sections of the corresponding fixed tumors occurred in both silver-stained and unreactive tumors, although the reaction was more prominent in the argyrophilic tumors. The results indicate that NSE in considerable amounts may be present in both argyrophilic and nonargyrophilic carcinomas of the breast, although higher concentrations are found most often in the former tumor type.