A study of different markers for neuroendocrine differentiation in breast carcinomas.

Forty-two breast carcinomas were studied with different markers for detecting neuroendocrine differentiation. The Bodian and Grimelius silver stains were applied, as well as immunostaining for neurone specific enolase (NSE), chromogranin, prealbumin and a battery of hormones. All cases were studied by electron microscopy as well. The material included 29 infiltrating ductal carcinomas, 10 infiltrating lobular carcinomas and 3 tubular carcinomas. Immunostaining for hormones was obtained in 11 cases (gastrin and PP (4 cases each), leu-enkephalin (3 cases), substance P (2 cases), beta-endorphin (2 cases), ACTH (1 case) and bombesin (1 case). Three cases revealed immunostaining for more than one hormone. Sixteen cases were positively stained with rabbit anti-NSE (Dako Corporation) and included all the 11 cases with proven immunoreactivity for hormones. 20 cases were positively stained with sheep anti-NSE and only 8 of the 11 cases with immunoreactivity for hormones were included. Immunostaining for prealbumin was observed in only 1 case and chromogranin in only 5 cases. All cases were unstained with the Bodian stain, whereas 3 cases showed a positive argyrophilic reaction with the Grimelius technique. Ultrastructural studies revealed typical small membrane-bound electron dense granules in cytoplasm in 4 cases, all among the 11 cases with immunoreactivity for hormones. We conclude that immunostaining with rabbit anti-NSE is the best screening method for detecting breast carcinomas with neuroendocrine differentiation.