Follicular Thyroid Carcinoma

Follicular Thyroid Carcinoma (FTC)

Epidemiology

  • Second most common thyroid cancer after papillary thyroid carcinoma.
  • Usually adults 40–60 years, slightly more common in women.

Pathophysiology / Genetics

  • Often associated with RAS mutations and PAX8-PPARγ rearrangements.
  • Generally spreads hematogenously → lung and bone metastases rather than lymph nodes (unlike papillary thyroid carcinoma).

Clinical Features

  • Usually presents as a slow-growing solitary thyroid nodule.
  • Cervical lymphadenopathy is uncommon.

Diagnosis

  • Fine-needle aspiration (FNA) cannot reliably distinguish follicular adenoma vs carcinoma → diagnosis often requires histopathology (capsular or vascular invasion).
  • Imaging: Ultrasound for thyroid evaluation; radioactive iodine scan if needed.

Staging & Prognosis

  • Prognosis generally good in minimally invasive disease.
  • Poorer prognosis in widely invasive FTC or distant metastases.

Treatment

  1. Surgery:
    • Total thyroidectomy preferred for tumors >1 cm or high-risk features.
    • Lobectomy may be sufficient for small, low-risk tumors.
  2. Radioactive iodine (RAI) ablation:
    • For remnant ablation and adjuvant therapy in high-risk patients.
  3. Thyroid hormone suppression therapy:
    • Levothyroxine to suppress TSH and reduce recurrence risk.
  4. Systemic therapy:

Monitoring

  • Thyroglobulin (Tg): tumor marker for recurrence or residual disease.
  • Periodic neck ultrasound and possibly RAI scans.
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