Endocrine Abstracts

Introduction: Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is an encapsulated or well-defined, not invasive neoplasm with a follicular growth pattern and core features of papillary thyroid carcinoma (PTC). This is considered to be a ’pre-malignant’ lesion of the RAS-like group. The RAS oncogene plays a huge role in human tumorigenesis. RAS gene mutations occur, in an average of 30–45% of follicular thyroid cancers (FTC). Among other molecular markers for thyroid cancer, there has been considerable interest in the potential clinical utility of RAS mutations as diagnostic and prognostic molecular markers. The role of RAS mutations in the clinical behavior of thyroid tumors is also unknown. How to properly manage these nodules is also controversial.

Objective: We present a case of a patient who was planning pregnancy when thyroid cancer was found with regular check up.

Case Report: Our patient was planning pregnancy, when a nodule with irregular margins was found in the thyroid gland during check up (TIRADs 4A - 0.7x0.9 cm). This nodule had no indication of fine needle aspiration (FNA), but as an enlarged lymph node with a lesion was also found, decision was made to perform FNA. FNA of nodule and lymph nodes revealed Bethesda VI-grade malignancy (follicular thyroid cancer - FTC). Total thyroidectomy and lymph node dissection was performed. Usually, after total thyroidectomy guidelines also recommend radioiodine therapy (RAI). But after the results of FNA, NIFTP was suspected and molecular testing was also performed, which typically involves TERT, BRAF, PAX8/PPARγ, RAS, and RET/PTC. In this patient RAS mutation was found and decision was made that RAI therapy may not be beneficial in this case, as RAS mutation is typical for NIFTP, and the likelihood of NIFTP recurrence is very low (<1%).

Conclusions: Studies over the past few years have illuminated the role of RAS mutations in the clinical behavior of thyroid tumors and the value of RAS mutations in advancing the management of thyroid nodules and thyroid cancer. We recommend considering diagnostic and prognostic molecular markers. RAS mutation-positive, differentiated thyroid cancer has a good prognosis and can be treated with less aggressive measures. RAS mutation-positive but cytologically benign thyroid nodules can be managed without radioactive iodine therapy.