Mammary gland hyperplasia leads to an increase in breast size. Mammary gland hyperplasia is a compensatory enlargement of the mammary glands due to abnormal changes in hormone levels in the body, which is very common during adolescence, so it is normal for the breast size to increase. In middle-aged patients, due to excessive hyperplasia of the breast gland and incomplete regeneration, degenerative changes in the gland will also lead to an increase in the size of the breast gland, and the patient will also experience significant breast swelling and pain with a certain regularity, especially during the premenstrual period. The diagnosis can be further confirmed by ultrasonography.