A key indicator of gynecomastia is noticeable swelling or increased breast size, often affecting both sides of the chest. This occurs due to the growth of breast gland tissue under the nipple and areola. You may observe sudden breast enlargement or a gradual increase over time. Initially, there is a small, firm lump beneath the nipple. As more tissue grows, it leads to puffy, swollen breasts. One of them may be larger than the other, but typically, both display some level of tissue accumulation. The skin can also become uneven and rippled.