Keloids are scars that spread beyond the expected limits of the incision. A raised scar 1/4 inch wide is a hypertrophic scar. A nodule the size of a marble at an ear piercing is a keloid.
Genetic predisposition is the most important factor. A patient who develops keloids from trivial injuries or from past surgery is likely to develop them after tummy tuck.
Good surgical technique, careful re-approximation of tissues will decrease the chances of keloids;. When they occur, treatment is available, though none are 100% successful.
Thanks for your question, vest wishes.