Please help! what is the treatment of choice for papillary carcinoma thyroid discovered in a hemi thyroidectomy specimen?

Need to clarify: I'm wondering why the hemithyroidectomy was performed in the first place, if not on suspicion of malignancy. The best treatment now will depend upon the pathologist's exact details of the little cancer. Perhaps doing nothing might be the best option, or going back to remove some lymph nodes. You may be asked your own preference in dealing with this cancer, which is less dangerous than most.

Options: Typically, if the carcinoma is 1cm or larger, then the other half of the thyroid is removed. If it is smaller than 1cm and unifocal (as opposed to multifocal), then the other side can be observed or removed. However, it really depends on multiple factors that you and your surgeon will have to discuss.

Depends on size.: If the tumor is less than 2 cm ( latest ATA guidelines), not multi focal, no poor histology, no lymph nodes, you can stop and be observed with just the hemi. If any of he above exceptions are true, you will likely need a completion thyroidectomy, +/- neck dissection, and radioactive iodine.