Partial Thyroidectomy With Incidental Metastatic Lymph Nodes

IMPORTANCE The need for completion thyroidectomy in patients with incidental metastatic lymph nodes after partial thyroidectomy is unclear.OBJECTIVE To investigate the outcomes of patients with incidental metastatic lymph nodes following partial thyroidectomy.DESIGN, SETTING, AND PARTICIPANTS A retrospective review of a prospectively maintained thyroid cancer database from 1985 to 2015 was carried out at a head and neck surgery practice at a tertiary referral cancer center. A total of 74 patients who underwent thyroid lobectomy or thyroid isthmusectomy between 1985 and 2015 and were found to have incidental metastatic lymph nodes on final pathologic analysis and were selected to be observed without immediate completion thyroidectomy were included. A separate group of additional 11 patients who underwent immediate completion thyroidectomy was also identified and reviewed.MAIN OUTCOME AND MEASURE Analysis took place from February to May 2022. Recurrence-free survival outcomes of patients found to have incidental metastatic lymph nodes on final pathologic analysis following partial thyroidectomy with no immediate completion thyroidectomy.RESULTS A total of 74 patients were observed, with a median (IQR) age of 39 (28-49) years; 44 (59%) were women. Sixty-four patients underwent thyroid lobectomy and 10 patients had isthmusectomy. Classic papillary thyroid carcinoma was the most common histologic type (34 [46%]). Vascular invasion and microscopic extrathyroidal extension were present in 11 patients (16%) and 22 patients (30%), respectively. Positive margins were identified in 5 patients (7.8%). Size of metastatic lymph nodes ranged between 0.07 cm and 1.2 cm. No extranodal extension was reported. A total of 52 patients (70%) were classified as intermediate risk for recurrence based on the American Thyroid Association risk stratification system. The median (IQR) follow up was 48.15 (15.4-86.1) months, during which only 1 patient had a regional recurrence. Another patient underwent delayed completion thyroidectomy for a contralateral lobe malignant abnormality. Recurrence-free survival, disease-specific survival, and overall survival were 97.4%, 100%, and 96.2%, respectively. A separate group of 11 patients who underwent immediate completion thyroidectomy were reviewed. These patients were more likely to have tall-cell papillary thyroid carcinoma (6 [55%] vs 13 [18%]), multifocality (9 [82%] vs 28 [41%]), microscopic extrathyroidal extension (8 [73%] vs 22 [30%]), and positive margins (3 [30%] vs 5 [7.8%]) compared with patients who were under observation only.CONCLUSION AND RELEVANCE Completion thyroidectomy may not be necessary in appropriately selected patients who are found to have incidental metastatic lymph nodes (N1a) after partial thyroidectomy for localized well-differentiated thyroid cancer.