A malignant cystosarcoma phyllodes with positive estrogen receptor and its heterotransplantation into nude mice.

We detected cytosol estrogen receptors in a malignant cystosarcoma phyllodes and succeeded in serial transplantations into athymic nude mice. The tumors of this transplantable strain (MC-3-JCK) have the same histologic features as the original tumors, and retain significant amounts of cytosol estrogen receptors. This strain appears to provide a useful experimental model for the study of biologic and therapeutic aspects of human cystosarcoma phyllodes of the breast.