The significance of argyrophilia in human breast carcinomas.

The significance of demonstrating argyrophilia in human breast carcinomas is a complex issue, although there is general agreement that "true" carcinoid tumours of the breast are rare. A predominantly unselected series of breast carcinomas has been investigated for evidence of argyrophilia using the Churukian Schenk method (Churukian and Schenk 1979), alpha lactalbumin and prealbumin, a marker of neuroendocrine cells. Argyrophilia has been detected in 25% of carcinomas, including all of mucinous types. However, only 4 of 68 tumours had a diffuse cytoplasmic reaction typical of that seen in neuroendocrine cells. The others showed a focal or subluminal/peripheral reaction. Those argyrophilic carcinomas with demonstrable alpha lactalbumin had this latter pattern of reactivity, although the milk protein was always detected in lesser amounts by comparison. Prealbumin was only found to varying degrees in eight tumours and the majority of these had a diffuse or focal cytoplasmic argyrophilic reaction. It would appear that in only a small number of breast carcinomas, approximately six percent, does the presence of argyrophilia probably represent neuroendocrine differentiation, whilst in others it is related to the secretory nature of the tumour cells.