A small round ball inside the left breast is considered to be a benign tumor occurring in the breast, also known as a mammary fibroadenoma. It appears as a lump with a smooth surface and an intact envelope. On palpation, the local texture will be tender, similar to the feeling of touching a rubber ball. In some patients, it may be associated with mild tenderness. Breast fibroadenoma occurs mainly in young people due to the imbalance between estrogen and progesterone levels in the body, and is most prevalent in the 20-25 age group. The most effective treatment for breast fibroids is surgery, which can be performed under local or epidural anesthesia, depending on the size of the lesion. Because it is very unlikely that breast fibroids will disappear on their own, if the lesion is relatively small and there are no clinical discomfort, it can also be observed temporarily and reviewed regularly.