[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Endocrine system](https://durgical.com/en/general-pathology/areas/endocrine/) › Follicular thyroid carcinoma and NIFTP # Follicular thyroid carcinoma and NIFTP - Lesion Follicular cancer looks like normal thyroid tissue. It is called cancer only if it breaks through its capsule or into blood vessels. Updated Nov 12, 2026 ## Key points - Follicular carcinoma = follicular cells plus capsular and/or vascular invasion. - Minimally invasive (capsular only), encapsulated angioinvasive, and widely invasive forms; vascular invasion worsens prognosis. - Haematogenous spread to bone, lung, liver; nodal spread is uncommon. - Iodine deficiency increases follicular carcinoma; RAS and PAX8-PPARG drivers. - Oncocytic carcinoma: Hürthle cells, same invasion criteria, takes up iodine less. - NIFTP: encapsulated, non-invasive, papillary-like nuclei, no true papillae or psammoma bodies; treated by lobectomy alone. ## What it is Follicular carcinoma is composed of follicular cells without papillary nuclear features and is diagnosed only by invasion: through the full thickness of the capsule or into capsular vessels. It spreads through blood to bone, lung and liver rather than to lymph nodes. NIFTP is an encapsulated, non-invasive tumour with papillary-like nuclei that was reclassified from carcinoma because it almost never recurs; its invasive counterpart is the encapsulated follicular variant of papillary carcinoma. ## Structure - Gross: solitary, encapsulated or infiltrative; widely invasive tumours extend into the soft tissue of the neck. - Micro: small follicles with little colloid, trabeculae or solid nests. - Capsular invasion must pass through the full thickness; vascular invasion means tumour in a capsular or extracapsular vessel, covered by endothelium or with thrombus. - Nuclei lack papillary features; psammoma bodies are absent. ## Encapsulated follicular-patterned thyroid tumours | Lesion | Nuclei | Invasion | Behaviour | | --- | --- | --- | --- | | [Follicular adenoma](https://durgical.com/en/conditions/thyroid-nodule/) | Bland | None | Benign | | [Follicular carcinoma](https://durgical.com/en/conditions/follicular-oncocytic-and-anaplastic-thyroid-carcinoma/) | Bland | Capsular and/or vascular | Malignant, blood-borne spread | | [NIFTP](https://durgical.com/en/conditions/thyroid-nodule/) | Papillary-like | None | Very low risk; not called carcinoma | | [Invasive encapsulated follicular variant of papillary carcinoma](https://durgical.com/en/conditions/thyroid-cancer/) | Papillary-like | Capsular and/or vascular | Malignant, RAS-like | | [Oncocytic carcinoma](https://durgical.com/en/conditions/follicular-oncocytic-and-anaplastic-thyroid-carcinoma/) | Oncocytic | Capsular and/or vascular | Malignant | ## Clinical notes - Presents as a cold nodule; sometimes the first sign is a bone metastasis. - Well-differentiated metastases often take up radioiodine, which is used for imaging and therapy. ## Memory aid A follicular tumour is innocent until it is caught breaking out of its cell (the capsule) or escaping down a vein. ## Test yourself Think of the answer, then tap the question to see it. ## What makes a follicular thyroid tumour a carcinoma? Invasion through the full thickness of the capsule or into capsular or extracapsular vessels. ## How does follicular carcinoma usually metastasise? Through the bloodstream, to bone, lung and liver. ## What is NIFTP? Non-invasive follicular thyroid neoplasm with papillary-like nuclear features: an encapsulated, non-invasive tumour reclassified from carcinoma because of its very low risk. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/follicular-thyroid-carcinoma-and-niftp/) [More Pathology questions →](https://durgical.com/en/practice/?f=pathology) ## Elsewhere in DurgiPedia - [Invasion and metastasis: the metastatic cascade, step by step](https://durgical.com/en/general-pathology/invasion-and-metastasis-the-metastatic-cascade-step-by-step/) - [Benign vs malignant tumours: the comparison table](https://durgical.com/en/general-pathology/benign-vs-malignant-tumours-the-comparison-table/) ## Connections ## Related 4 - [Thyroid nodule and follicular adenoma](https://durgical.com/en/general-pathology/thyroid-nodule-and-follicular-adenoma/) - [Papillary thyroid carcinoma](https://durgical.com/en/general-pathology/papillary-thyroid-carcinoma/) - [Thyroid cancer: genetics and radiation](https://durgical.com/en/general-pathology/thyroid-cancer-genetics-and-radiation/) - [Invasion and metastasis: the metastatic cascade, step by step](https://durgical.com/en/general-pathology/invasion-and-metastasis-the-metastatic-cascade-step-by-step/) ## Related conditions 3 - [Follicular, oncocytic (Hürthle cell) and anaplastic thyroid carcinoma](https://durgical.com/en/conditions/follicular-oncocytic-and-anaplastic-thyroid-carcinoma/) - [Thyroid cancer (papillary)](https://durgical.com/en/conditions/thyroid-cancer/) - [Thyroid nodule](https://durgical.com/en/conditions/thyroid-nodule/) [← All of general pathology](https://durgical.com/en/general-pathology/) Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Thyroid Cancer Treatment (PDQ®)–Health Professional Version](https://www.cancer.gov/types/thyroid/hp/thyroid-treatment-pdq) (National Cancer Institute, 2025); [Thyroid Nodule](https://www.ncbi.nlm.nih.gov/books/NBK535422/) (StatPearls (NCBI Bookshelf), 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/general-pathology/follicular-thyroid-carcinoma-and-niftp/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/follicular-thyroid-carcinoma-and-niftp/