Immunocytochemical evidence for neuroendocrine differentiation in human breast carcinomas.

Normal and neoplastic human breast tissues have been stained with antibodies recognizing neuroendrocrine differentiation. Fifteen out of 44 (34 per cent), breast carcinomas stained positively with monoclonal antibody LICRLON-E36, and 11 out of 44 (25 per cent) of these tumours stained with an antibody raised against neuron-specific enolase (NSE). Eight tumours stained positively with both antibodies. No correlation was observed between staining with these antibodies and the tumour histology, nor with the degree of cellular differentiation as indicated by staining with several cell surface directed monoclonal antibodies. Ultrastructural analysis of a series of breast tumours showed the presence of membrane-bound dense-core vesicles in almost all tumours, including E36 and NSE positive and negative tumours. The presence of these structures appears to be of little value in predicting neuroendocrine differentiation.