The treatment for a thyroid nodule will depend on whether it is benign, malignant [cancer], or indeterminate.
A benign pathology result means that there is no evidence of cancer. Most patients with a benign result will not need surgery, unless the nodule is large and causing compressive problems in the neck or if it is bothersome. The type of surgery will depend on the location of the nodule and whether there are multiple or bilateral nodules in the thyroid, If only one side of the thyroid is affected, a thyroid lobectomy is used to remove the affected side of the thyroid. If multiple, bilateral nodules are present, a total thyroidectomy is used.
Typically, when the biopsy demonstrates a cancer, it is either a papillary thyroid cancer (most common) or a medullary thyroid cancer. Most thyroid cancers will be treated with a total thyroidectomy and possible removal of some of the lymph nodes in the neck. The addition of additional postoperative therapy will ultimately depend on the type of cancer, how big the cancer is, and if there is any spread outside the thyroid.
There are a number of different types of tumors that are considered indeterminate on FNA: follicular neoplasm, Hurthle cell neoplasm, and atypical lesion. An indeterminate lesion means that the FNA cells do not look completely normal, but that in order to make a diagnosis of cancer the whole nodule has to be examined under the microscope to see if there is invasion or growth outside of the nodule. This can only be done by removing part or all of the thyroid through a thyroid lobectomy (most commonly), or, if needed, a total thyroidectomy.