Morphological and molecular characteristics of subcutaneous implantation of nodules after endoscopic thyroidectomy in 3 cases

Objective To investigate the pathological and molecular characteristics of subcutaneous implanted thyroid lesions after endoscopic thyroid surgery. Methods A retrospective analysis was conducted on three postoperative implantation cases diagnosed in the Department of Pathology of our hospital from 2017 to 2024. Morphological evaluation, immunohistochemical staining, and next generation sequencing (NGS) targeting 66 cancer-related genes and 177 fusion loci were performed to compare features between primary and implanted lesions. Results All three implanted lesions exhibited morphological similarity to their primary counterparts, but displayed enriched mutational profiles. Case 1: a 13-year-old female. The primary lesion was an atypical follicular adenoma progressing to follicular carcinoma, while the implanted lesion was follicular carcinoma. Both lesions harbored MEN1 mutations, with an additional PTPRT mutation detected in the implanted lesion. Case 2: a 45-year-old male. The primary lesion was bilateral nodular goiter, and the implanted lesion showed follicular epithelial hyperplasia with a 0.3 cm papillary carcinoma focus. No mutations were identified in the primary lesion, whereas the implanted lesion exhibited MEN1, GLIS3, EZH1, and KMT2C mutations. Case 3: a 42-year-old female. The primary lesion included a left thyroid adenoma with cystic degeneration and right nodular goiter. A nodular goiter-like implanted lesion was detected in the right breast 5 years postoperatively. The primary lesion harbored TERT, GLIS3, and SPOP mutations, while the implanted lesion showed TERT, GLIS3, EIF1AX, and KMT2C mutations. Conclusions Endoscopic thyroid surgery is widely applied in clinical practice, however, implantation dissemination of thyroid lesions along surgical pathways may occur, encompassing both benign and malignant entities. Implanted lesions exhibit pathological similarities to their primary counterparts, but demonstrate mutational enrichment.