Thyroid nodules are a common and usually represent a benign condition. They are accurately assessed by fine needle aspiration (FNA) cytology. Most benign nodules fall under follicular nodular disease, which includes colloid goitre and adenomatoid nodules. A benign FNA diagnosis carries a very low risk of malignancy (0–3%). These cases typically requires only the clinical followup. This diagnostic category/report relies on identifying benign follicular cells without atypia, mixed with colloid. The presence of mild cytological changes usually excludes a benign diagnosis. Care is needed to avoid over-diagnosis in cases with minimal nuclear changes or degenerative features. Test your learning and check your understanding of this book’s contents: use the “Springer Nature Flashcards” app to access questions using ▶ https://sn.pub/7pox8x . To use the app, please follow the instructions in Chap. 1 .