Removed gland does not grow back, but new tissue can form if the hormonal driver is still running. That is why the blood work comes before the scalpel.
Tissue that has been excised is gone permanently; it does not regenerate. Two other things can happen and both get called recurrence. Fat can return if you gain weight, because the fat cells left behind for contour still expand. And genuinely new glandular tissue can form if the hormonal environment that produced the first gland is still present. Distinguishing the two is straightforward on examination, and they have completely different solutions.
Before we book an operating theatre we want testosterone, oestradiol, LH, FSH, prolactin, thyroid function and liver enzymes, plus hCG if the presentation is one-sided and recent. Most results come back normal and the case is idiopathic. When they do not, the finding usually points somewhere specific: a prolactinoma, hypogonadism, a thyroid problem or liver disease. Operating without that information means treating the visible sign and leaving the cause running.
Leaving too little gland causes a crater under the nipple; leaving too much leaves a palpable lump that patients read as regrowth. A thin layer of tissue must stay directly behind the areola to support it, and judging that thickness is the part of the operation that separates experienced hands from inexperienced ones. Most revision cases we are asked to correct are not hormonal at all — they are contour problems from the first surgery.
Keep your weight stable, keep off anabolic compounds, and treat any hormonal condition the pre-operative work-up found. Those three things cover almost every avoidable recurrence. Swelling and firmness in the first three months are not recurrence — they are healing, and they settle with the compression vest. If a new firm disc appears after month six, send us a photograph and we will arrange an ultrasound rather than guess from a description.
Contour is broadly settled at three months and fully settled at six to twelve, once swelling has resolved and the scar has matured. Judging the shape before month three is premature.
Training itself does not cause recurrence. Anabolic compounds used alongside training do, which is the distinction that matters when men ask this question.