This lesion is solid, mixed density and and ultrasound guided needle biopsy shows an atypical fibroepithelial lesion and surgical excision followed. The second lesion was not found on ultrasound and the recommendation was that a follow up ultrasound be done in 6 months. The case was classified Birads III. Are you satisfied?
The case should have been called Birads 0 and further workup should have been done to identify and sample (if appropriate) the lesion not seen on initial ultrasound. This is inappropriate use of Birads III. In fact there is no diagnosis at all of the second lesion. Management options at this stage would depend on resources at your disposal and where you work. MRI would be helpful and even second look ultrasound after MRI. If all else fails and you have no resources you should localize this lesion under mammographic guidance and have it removed. The teaching point is that extra imaging should have been done at this stage.