--- title: "Follicular Thyroid Carcinoma" description: "ENT notes on Follicular Thyroid Carcinoma - Risk factors, Clinical Features, Histology, Investigations and Treatment." source: "The ENT Resident" author: "Dr. Mausumi Das" canonical_url: "https://www.theentresident.com/ent-notes-lectures/follicular-thyroid-carcinoma" categories: ["Thyroid"] video: "https://www.youtube.com/watch?v=6Dub31PaVVU" image: "https://media.theentresident.com/og-images/follicular-thyroid-carcinoma.png" --- # Follicular Thyroid Carcinoma ENT notes on Follicular Thyroid Carcinoma - Risk factors, Clinical Features, Histology, Investigations and Treatment. Watch the full video lecture on YouTube: https://www.youtube.com/watch?v=6Dub31PaVVU ## ๐Ÿง  Follicular Thyroid Carcinoma (FTC) ### ๐Ÿ“Š Epidemiology of Follicular Thyroid Carcinoma - The second most common thyroid carcinoma - **Incidence:** 10โ€“15% of all thyroid malignancies. - **Age:** Mean = 50 years (6th decade). Rare <30 years. - **Sex:** Female : Male = **3 : 1** - **Origin:** From follicular cells of thyroid. - **Key Difference:** **Nuclear features of papillary carcinoma are absent.** >What are the histopathological features of Papillary Thyroid Carcinoma? --- ### โš ๏ธ Risk Factors of Follicular Thyroid Carcinoma - **Radiation exposure** to head/neck. - **Iodine deficiency:** More common in iodine-deficient areas (25โ€“40% of thyroid cancers). - **Genetic Mutations** - **Syndromic Associations** >Which genetic alterations are commonly associated with Follicular Thyroid Carcinoma? >What Familial syndromes are associated with Follicular Thyroid Carcinoma? --- ### ๐Ÿฉบ Clinical Features of Follicular Thyroid Carcinoma **Presentation:** - Painless, slow-growing thyroid nodule (cold on scintigraphy). - Rapid increase in size of a long-standing nodule = malignant change. **Metastasis:** - **Lymph node mets:** rare (โ‰ˆ4%). - **Distant mets:** common (10โ€“15% at presentation). - **Spread:** hematogenous >Which are the common sites for distant metastasis in Follicular Thyroid Carcinoma? --- ### ๐Ÿ”ฌ Histology of Follicular Thyroid Carcinoma **WHO 2017 Classification** 1. **Minimally invasive** (most common) โ€“ capsular invasion. 2. **Encapsulated angioinvasive** โ€“ vascular invasion <4 vessels. 3. **Widely invasive** โ€“ extensive capsular/vascular invasion โ‰ฅ4 vessels โ†’ aggressive, high mets risk (29โ€“66%). **Macroscopy** - Encapsulated solid lesion with thick capsule. - Cut section: gray/tan, colloid-filled follicles, fibrosis, calcification, cystic change, hemorrhage. **Microscopy** - Uniform cells; **no papillary nuclear features.** - Growth patterns: trabecular, micro/macrofollicular, normofollicular. - **Invasion:** capsular, vascular, adjacent thyroid tissue. - **No** necrosis, squamous metaplasia, psammoma bodies. >What are the **Histological Variants of Follicular Thyroid Carcinoma** ? --- ### ๐Ÿงช Investigations of Follicular Thyroid Carcinoma - **FNAC:** Cannot differentiate adenoma vs carcinoma โ†’ need histology (capsular/vascular invasion). - **Ultrasound:** Solitary, well-defined, iso-/hyperechoic, halo sign, increased internal vascularity. - **Thyroid function test:** Often euthyroid, sometimes hyperthyroid. - **X-ray chest:** Pulmonary mets. - **CT/MRI:** Extent, retrosternal extension. - **Bone scan:** For bone metastasis. --- ### ๐Ÿ’Š Treatment of Follicular Thyroid Carcinoma **1- Surgery** - **Hemithyroidectomy:** Only if <1 cm, unifocal, no extra-thyroidal spread, no mets. - **Total thyroidectomy (preferred)** >What are the indications of Total Thyroidectomy in Follicular Thyroid Carcinoma? **2- Neck Dissection** - **Central neck dissection** if: tumor >4 cm, extrathyroidal spread, aggressive histology, positive nodes. - **Lateral dissection** not routine. **3- Hormone Therapy** - **TSH suppression:** - Thyroxine 2 mcg/kg - Liothyronine 20 mcg TDS until histopathology confirmed. **4- Radioiodine Ablation (I-131)** - Only after **total thyroidectomy**. - Given 6โ€“8 weeks post-op. >What are the indications of Radioiodine ablation in Follicular Thyroid Carcinoma? **5- External Beam Radiotherapy** - For unresectable, non-radioiodine avid, or recurrent disease. - **IMRT preferred.** --- ### ๐Ÿ“Š Treatment Algorithm - **FNAC = Follicular Neoplasm:** โ†’ Hemithyroidectomy โ†’ If carcinoma โ†’ Completion thyroidectomy + RAI. - **FNAC = Follicular Carcinoma:** โ†’ Direct total thyroidectomy. - **Elderly, >4 cm nodule, FNAC = Follicular Neoplasm:** โ†’ Total thyroidectomy. --- ## ๐Ÿ”Ž Treatment Response & Follow-up of Follicular Thyroid Carcinoma 1. **Post-RAI Scan:** Detects residual/metastatic disease. 2. **Stimulated Thyroglobulin (Tg):** tumor marker for differentiated thyroid cancer (most sensitive when stimulated) 3. **CT Scan:** If Tg unreliable or RAI uptake beyond neck. >What are the different response categories while assessing treatment outcome in Follicular Thyroid carcinoma? What is the follow up protocol in each group? --- ### ๐Ÿ“‰ Prognosis of Follicular Thyroid Carcinoma **Poor Prognostic Factors** - **Clinical:** - Age >50 - Male sex - Tumor >4 cm - Extrathyroidal extension - Distant metastasis at presentation - **Pathological:** - Vascular/capsular invasion - Anaplastic transformation - Trabecular growth pattern --- ## About This Note This free ENT note on Follicular Thyroid Carcinoma was written by Dr. Mausumi Das and is paired with a corresponding video lecture. 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