Immunohistochemical demonstration of chromogranin in endometrial carcinomas with argyrophil cells

Forty-five endometrial carcinomas, 36 of which contained argyrophil cells and nine of which were nonargyrophilic by the Grimelius method, were examined immunohistochemically for chromogranin. Chromogranin immunoreactivity was present in 19 of the 36 tumors with argyrophil cells (53 per cent) and in none of the nine tumors lacking these cells. All six of the tumors that contained argyrophil cells resembling enterochromaffin cells were chromogranin-positive, with the staining corresponding to the argyrophilia. In contrast, only 13 of the 30 tumors in which argyrophilia was present in the apical region or throughout the cytoplasm of the cells showed chromogranin immunoreactivity. In seven of these tumors, an excellent correlation existed between the distribution of argyrophilia and chromogranin positivity, but in the other six tumors argyrophilia was more pronounced than chromogranin immunoreactivity. Adjacent to one tumor, unusual cells in which argyrophil granules were packed predominantly in the basal portion of the cytoplasm were encountered in a focus of atypical hyperplasia; these cells were also chromogranin-positive. The present observations suggest that endometrial carcinoma cells with diffuse or apical chromogranin immunoreactivity may represent an early stage in the development of cells resembling those of the enterochromaffin type.