Argyrophilic cells in mammary carcinoma.

Breast tumor tissues were treated by the Grimelius procedure and examined for the presence of argyrophilic cells. Carcinomas found to contain argyrophilic cells did not include classic carcinoid tumors; the group was, in fact, heterogeneous, comprising poorly differentiated ductal carcinomas, lobular carcinomas, carcinomas of uncertain origin, and colloid carcinomas. Colloid tumors were the most frequently encountered. The prominence of argyrophilic cells in colloid carcinomas raises the possibility that development into mucin-producing cells is propitious for endocrine differentiation.