Management of microcarcinomas (papillary and medullary) of the thyroid

Purpose of review Microcarcinomas of the thyroid gland are defined by the size criteria as tumors measuring less than 1 cm in greatest dimension. The clinical significance of papillary thyroid microcarcinoma (PTMC) and medullary thyroid microcarcinoma (MTMC) is debatable. Variation in practice patterns exist in the United States with regard to diagnosis, treatment, and long-term management. We review the most recent guidelines on the management of these controversial malignancies. Recent findings PTMC has recently been shown to be the most common thyroid malignancy in patients older than 45 years in the United States. The management of patients with PTMC is not well defined, although recent studies have indicated that total or near-total thyroidectomy decreases overall recurrence rate. BRAF(V600E) mutation testing plays an increasingly important role in perioperative management and has potential for targeted molecular therapies. Prophylactic thyroidectomy is indicated early in life for RET mutation carriers at risk for medullary thyroid cancer. New evidence suggests that timing may be personalized based on specific exon mutations and serum calcitonin levels. The biological significance and surgical management of MTMC have been debated, but the most recent studies indicate a relatively high incidence of lymph node metastases, distant metastases, and persistently elevated postoperative calcitonin; and argue for the aggressive management of even the smallest MTMCs. Summary Total or near-total thyroidectomy is the treatment of choice in patients with PTMC in order to eradicate multifocal disease and decrease overall recurrence rate. If there are palpable, biopsy-proven, or grossly apparent metastases at the time of operation, central lymphadenectomy should be performed. Prophylactic thyroidectomy in hereditary cases of MTMC may be guided by knowledge of specific exon mutations and calcitonin levels. The extent of operation for both hereditary and sporadic MTMC is nonstandardized, and further studies are needed to clarify this issue.