Thyroid cytology: a review of current international reporting systems and emerging developments.

Fine needle aspiration (FNA) is a widely available initial diagnostic tool for the investigation of thyroid nodules. The findings are paramount for appropriate patient management, which is best determined in the multidisciplinary setting. However, while international classification systems utilise similar criteria, there are areas, particularly in the management of the 'indeterminate' category, which require resolution. This review article compares the current classification systems used worldwide and explores how the developing fields of molecular/sequencing techniques, as well as the use of rapid on-site assessment, may improve our diagnostic certainty.