7355 A Case of High-Risk Thyroid Tumor Markers Found in Subcutaneous Thyroid Implants in a Patient with Benign Thyroid Pathology
Authors: Fedorko J , Fatima S , Amblee A P , Poku C A 
Published: October 2024

Disclosure: J. Fedorko: None. S. Fatima: None. A.P. Amblee: None. C.A. Poku: None.

Background: While fine needle aspiration (FNA) remains the primary diagnostic tool for thyroid malignancies, the utilization of molecular markers has become increasingly common in the workup of thyroid nodules. They play a useful role in distinguishing between malignant and benign pathology when cytology is indeterminate and in formulating treatment plans. The vast majority of research for these genetic markers is conducted in cases with thyroid malignancy. However, there have been numerous cases where these genetic markers were identified in benign thyroid tissue. Case: A 73-year-old male with left hemithyroidectomy (benign left nodule) presented 6 years later with new superficial neck nodules along the midline, left thyroid bed and R thyroid lobe. FNA of the right thyroid nodule was benign. Three months later the patient underwent an excision of the midline neck nodules which revealed thyroid tissue arranged in nests of fibrotic tissue without definite features of papillary thyroid carcinoma. Molecular analysis (Thyroseq) was positive for HRAS, E1F1AX and TERT mutations thus metastatic follicular carcinoma was suspected. The patient underwent complete thyroidectomy. Pathology revealed normal thyroid tissue and a diagnosis of thyroid neck implants was made. Given the benign pathology, the plan was for close follow-up with neck imaging every 6 months. Discussion: Thyroid tissue implants can rarely be caused by previous surgical interventions, especially partial thyroidectomy. There is literature documenting similar clinical cases in which subcutaneous thyroid implants are found in patients after undergoing total or subtotal thyroidectomy. In one case series, there were cases in which thyroid implants were discovered 26 years post-surgery, with most of the cases reporting benign pathology. Given our patient’s presentation and clinical history, the possibility remains that his subcutaneous tissue findings were caused by his prior partial thyroidectomy. A recent article reviewed 60 publications and &gt;8000 patients for the prevalence of high-risk tumor markers (RAS mutation, RET/PTC, and PAX8/PPAR-gamma chromosomal rearrangements) in benign thyroid tissue. They concluded that prevalence findings were highly variable, warning providers to exercise caution when using these genetic markers to guide diagnosis and treatment decisions. Conclusion: While certain high-risk genetic tumor markers are increasingly used to help identify thyroid malignancies, it is important to keep in mind that these genetic markers are not exclusively found in cancerous tissue, and should not be used as the sole diagnostic tool for diagnosis and treatment. While it is imperative that metastatic disease is ruled out, it is essential to consider other pathologies when evaluating recurrent thyroid and neck masses in patients with a history of benign thyroid lesions.

Presentation: 6/3/2024