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Follicular thyroid carcinoma (FTC) is a malignant epithelial neoplasm of the thyroid derived from follicular cells, characterized by capsular and/or vascular invasion. Unlike papillary thyroid carcinoma (PTC), FTC typically exhibits hematogenous spread rather than lymphatic, and lacks the nuclear features of PTC.

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Epidemiology

• Second most common thyroid cancer (∼10–15% of differentiated thyroid carcinomas)
• More common in women (F:M ~3:1)
• Peak incidence: 40–60 years
• Higher prevalence in regions with iodine deficiency

Etiopathogenesis

Risk Factors

• Iodine-deficient diet
• Radiation exposure (less commonly than PTC)
• Genetic mutations:
  • RAS mutations
  • PAX8/PPARγ rearrangement

Pathology Spectrum

• Minimally invasive FTC: limited capsular invasion
• Widely invasive FTC: extensive capsular and vascular invasion
• Hürthle cell carcinoma: Oncocytic variant with more aggressive behavior

Pathology

Gross