Chromogranin A, neuron-specific enolase and synaptophysin as neuroendocrine cell markers in the diagnosis of tumours of the gastro-entero-pancreatic system

Neuroendocrine (NE) tumours of the gastro-entero-pancreatic tract were analysed immunohistochemically for the expression of chromogranin A, neuron-specific enolase and synaptophysin. In all cases at least one marker was present and in 17 out of 19 investigated neoplasms, at least one of the three markers could be demonstrated in more than 75% of the NE tumour cells. Monoclonal antibody chromogranin A stained a much higher proportion of NE cells in tumours with hormonal activity than in hormonally inactive ones. Immunostaining of the primary tumour as compared to its respective metastases was almost identical. Thus, chromogranin A, neuron-specific enolase and synaptophysin identify NE tumours and their metastases regardless of their localization and their state of hormonal activity. As 'panendocrine' markers of NE tumours they are of special diagnostic value in NE tumours that do not produce hormones and peptides.