BRAFV600E mutation: a potential predictor of more than a Sistrunk's procedure in patients with thyroglossal duct cyst carcinoma and a normal thyroid gland.

Abstract

To assess the utility of mutational markers in determining the most appropriate initial surgery for patients with thyroglossal duct cyst carcinoma (TGDCCa) and a normal thyroid gland. Our sample comprised 15 patients with a diagnosis of TGDCCa and a thyroid gland histologically negative for any malignant involvement, who underwent surgery between the years 1994 and 2017. Clinical records were reviewed and tissue specimens were genetically tested for the presence of the most commonly encountered mutational markers in differentiated thyroid cancer: BRAF, N-RAS, and H-RAS. The primary outcome of interest was the correlation between mutational marker positivity and the T-stage of the primary tumor and its potential implication on therapeutic decision making. All 15 cases were papillary carcinomas with a mean tumor size of 17mm (2-40mm). According to the 7th edition of the American Joint Committee on Cancer TNM staging system, these represented: T1 (n = 3), T2 (n = 1), and T3 (n = 11). Cancerous invasion of the pericystic soft tissue and/or hyoid bone was considered T3. BRAFV600E was the only mutational marker identified (7 in 15 cases). All BRAFV600E-positive lesions were T3, necessitating radioactive iodine ablation (RIA) therapy, therefore, total thyroidectomy. The correlation between BRAFV600E positivity and extracystic cancerous extension was statistically significant [1.0 (7/7) vs. 0.5 (4/8); p value = 0.0035]. BRAFV600E positivity seems to be predictive of locally advanced disease mandating RIA therapy. Therefore, it could serve as a preoperative tool that predicts the need for total thyroidectomy, in addition to Sistrunk's procedure.