Estrogen receptor activity in primary argyrophil carcinoma of the breast

Of seven primary breast neoplasms with exceptionally high estrogen receptor activity (> 350 fm/mg protein), all displayed positive argyrophilia with the Grimelius stain and a negative argentaffin reaction by the Fontana method. Two of the seven had a typical carcinoid pattern in conventional histologic sections, and both ultrastructually revealed cytoplasmic granules, 200-350 nm, often with a moderately dense core and a pale halo intervening between the core and the limiting membrane. Of the remaining five, four were originally diagnosed as breast carcinomas of "no special type" (NST), the fifth as a mucinous carcinoma. Reinspection confirmed the mucinous tumor, but the NST tumors revealed a densely hyalinized stroma with intervening trabeculae composed of small cells containing argyrophil-positive cytoplasmic granules. We propose to test the hypothesis that argyrophil cell carcinomas will regularly demonstrate estrogen receptor activity, often at high levels.