[Surgical approach selection and prognosis analysis of papillary thyroid microcarcinoma in the isthmus]

Objective:To compare the prognosis of papillary thyroid microcarcinoma of the isthmus（PTMCI） after different surgical methods, and to investigate the most appropriate surgical plan for it, so as to provide reference for the selection of clinical surgical plan. Methods:The clinical data of 106 PTMCI patients diagnosed with postoperative pathology after surgical treatment in Department of Otolaryngology Head and Neck Surgery, Ningbo Medical Center Lihuili Hospital from January 2016 to June 2023 were retrospectively analyzed. The patients were divided into 3 groups according to whether there were nodules in the lateral lobe of the thyroid gland, namely, isolated PTMCI group, PTMCI group with unilateral lobe nodules, and PTMCI group with bilateral lobe nodules. Combined with follow-up information, the differences of recurrence rate, survival rate and postoperative complications after different surgical methods were compared among all groups. The surgical procedures included isthmic thyroidectomy, isthmic + unilateral lobectomy, and total thyroidectomy. All patients underwent central lymph node dissection at the same time. Results:There were no significant difference in recurrence rate, survival rate and postoperative complications among all groups and between groups. Postoperative recurrence occurred in 2 patients, among which 1 patient was PTMCI with multiple focal tumors in unilateral lobe undergoing isthmus + unilateral lobectomy + ipsilateral central lymph node dissection. The recurrence was manifested as contralateral cervical lymph node metastasis. Another case of PTMCI with bilateral benign nodules underwent isthmus + unilateral lobe（larger nodule） resection + ipsilateral central lymph node dissection, and the recurrence was manifested as residual glandular recurrence. One patient developed permanent hoarseness after surgery. The postoperative pathology of 31 patients（29.2%） indicated multiple focal thyroid carcinoma. Postoperative pathology of 41 patients（38.7%） suggested lymph node metastasis in the central region of neck. The disease-specific survival rate was 100%. Conclusion:Isthmic thyroidectomy is recommended for isolated PTMCI. Isthmus of thyroid+ unilateral lobectomy is feasible for PTMCI with unilateral lobectomy. If multiple suspicious malignant nodules（≥3） occur in unilateral lobectomy, total thyroidectomy is recommended. Total thyroidectomy is feasible for PTMCI with bilateral nodules. All PTMCI patients should undergo prophylactic central cervical lymph node dissection at the same time.