Focal pregnancy-like changes in the breast.

The aetiology of focal, preganancy-like mammary changes in non-pregnant and non-lactating women is discussed on the basis of the literature and a material of 31 patients. Such changes were found in one or more glandular lobules in 3 per cent of the breast tissue specimens received in our departments. As a rule, this finding was made in women who had been pregnant and who had been or were on oestrogenic or on contraceptive medication. They occurred in fertile, menopausal, as well as in post-menopausal women. Often they were seen many years after the pregnancy and/or intake of hormones. They were observed also in women who had never been pregnant or on hormone medication, and even in men on oestrogen therapy. It is likely, therefore, that focal pregnancy-like changes in non-pregnant and non-lactating women indicate a selective susceptibility of the mammary glandular tissue to oestrogen. Accordingly, we interpret the change as a normal histological variant.