RAS-positive thyroid nodules.

Purpose of Review: The current review focuses on the uncertainty regarding the management of rat sarcoma viral oncogene homolog RAS-positive thyroid nodules. The application of oncogene testing has been heralded for improving risk assessment for indeterminate cytology thyroid nodules and has grown in clinical use. RAS mutations are historically considered oncogenic. However, RAS mutation detection in thyroid nodules has proven problematic, as these mutations are found in benign and malignant lesions.
Recent Findings: RAS-positive thyroid nodules frequently have indeterminate cytology and a finding of a positive RAS mutation identifies a significant number of benign lesions as well as thyroid cancers. Long-term follow-up of RAS-positive nodules with benign cytology shows an indolent course not consistent with eventual malignant transformation. Many RAS-positive nodules previously diagnosed as follicular variant of papillary thyroid carcinoma now will be reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features, indicating a more indolent nature of these RAS-positive lesions.
Summary: Recent findings have underscored that diagnosis of a RAS-positive thyroid nodule is not synonymous with thyroid malignancy. The ideal clinical and surgical management of these nodules remains challenging.