Enlarging occult fibroadenomas.

From July 1, 1989, through June 30, 1991, 1,218 preoperative wire-localization breast biopsies were performed at one institution. In this group, 254 (21%) of the abnormalities were fibroadenomas, 26 of which had enlarged or developed in the interval between routine or short-interval follow-up mammography. This interval growth was noted in 21 premenopausal women and in five who were postmenopausal and receiving oral estrogen supplementation.