Hi Sharon:
My daughter had one at age 15 (she is 19 now) It was discovered during a routine physical for school sports. We did not notice it, but after the dr. pointed it out you could see that she had a slight bump on one side of her neck.
She had to go through several rounds of diagnostics: an ultrasound, then a scan involving radioactive iodine. Both tests were inconclusive, so the surgeon recommended that it be removed. She had surgery to remove half of her thyroid. She was in the hospital overnight, and out of school for about a week.
The nodule turned out to be benign, and her thyroid levels have been completely normal since, so no follow-on treatment necessary.
She has a two-three inch scar at the base of her neck, but it has faded quite rapidly. The surgeon told us that ultimately it would be a very thin line.