BRAF Mutated Tall Cell Papillary Carcinoma Lung Metastasis Following Thyroidectomy

Abstract

SESSION TITLE: Metastatic and Other Primary Lung Tumors SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: BRAF Mutated Tall Cell Papillary Carcinoma is a rare tumor infrequently presented as lung metastasis. Although Papillary Carcinoma is one of the most frequent Thyroid Cancers, BRAF-Tall Cell Variant carries the worst prognosis. CASE PRESENTATION: A 65-year-old male former 12-pack year smoking history and total thyroidectomy as a child presents for evaluation of hematochezia. He has no prior history of radiation exposure or familial history of thyroid cancer. Supplemental thyroid replacement therapy was started at age 21 due to clinical hypothyroidism. Residual thyroid glandular tissue was not visible on CT scan or ultrasound studies. Abdominal and pelvic computed tomography (CT) scan demonstrated the incidental finding of a 1.2 cm non-calcified lobulated and speculated pulmonary nodule. Positron Emission Test (PET) Scan demonstrated maximum SUV uptake of 11.0 in mediastinal and pretracheal structures. Mediastinoscopy aborted after experiencing intraoperative bleeding complications. Endobronchial Ultrasound Trans-bronchial fine needle aspiration (EBUS-TB FNA) was was non-diagnostic. Exploratory thoracotomy with right middle lobe wedge resection and mediastinal lymph node dissection was performed. Surgical biopsy diagnosed a poorly differentiated tall cell papillary carcinoma, BRAF positive mutation. DISCUSSION: BRAF is a important oncoprotein responsibile for the MAPK-pathway output. Its role suppresses the expression of genes required for iodide incorporation. Due to poor iodide uptake, radioactive iodine is not useful diagnostically or therapeutically in tall cell variant disease. CONCLUSIONS: BRAF-mutated classical or tall-cell-variant papillary thyroid carcinomas have a high frequency of lymph-node metastases and recurrence after thyroidectomy. These associated carcinomas have a poor response to radioiodine therapy due to the high MAPK-pathway output, which is driven by the BRAF V600E oncoprotein. This case demonstrates the difficulty with diagnosis of mediastinal lymphadenopathy and rare presentation of tall cell variant papillary cell carcinoma as lung metastasis. Reference #1: American Cancer Society: Cancer Facts and Figures 2016. Atlanta, Ga: American Cancer Society, 2016. Reference #2: Gimm, O., Rath, F. W. and Dralle, H. (1998), Pattern of lymph node metastases in papillary thyroid carcinoma. Br J Surg, 85: 252-254. doi:10.1046/j.1365-2168.1998.00510.x Reference #3: Xing M, Westra WH, Tufano RP, et al. BRAF mutation predicts a poorer clinical prognosis for papillary thyroid cancer. J Clin Endocrinol Metab 2005;90:6373-9. DISCLOSURE: The following authors have nothing to disclose: Brandon Hooks No Product/Research Disclosure Information