Thyroid Nodules and Cancer

Thyroid Nodule Basics - Lump Sum Assessment

• Solitary Thyroid Nodule (STN): Common; prevalence ↑ with age. Most are benign.
• Malignancy Risk Factors:
  • Age < 30 or > 60 yrs
  • Childhood head/neck radiation
  • Family Hx (thyroid Ca, MEN2)
  • Rapid growth, hoarseness
• Initial Workup:
  • History & Physical Exam: Note size, consistency, mobility, lymph nodes.
  • Serum TSH: Initial biochemical test.

⭐ Most thyroid nodules are benign, but all require systematic evaluation.

Nodule Sonography & Cytology - Pixel & Prick Pointers

Thyroid USG: Risk stratifies nodules. High-risk features: microcalcifications, marked hypoechogenicity, irregular margins, taller-than-wide, extrathyroidal extension, suspicious nodes. ACR TI-RADS (TR1-TR5) score guides FNAC.

Fine Needle Aspiration Cytology (FNAC):

• Indicated for suspicious nodules (e.g., TI-RADS ≥TR3 or high-risk USG features).
• Usually USG-guided biopsy.

⭐ FNAC is the gold standard for pre-operative differentiation of benign vs. malignant thyroid nodules.

Bethesda System for Reporting Thyroid Cytopathology (BSRTC): Reports cytopathology, Risk of Malignancy (ROM) & guides management.

• I: Non-diagnostic (ROM ~10%)
• II: Benign (ROM <3%)
• III: AUS/FLUS (ROM ~20%)
• IV: Follicular Neoplasm/Suspicious (ROM ~30%)
• V: Suspicious for Malignancy (ROM ~65%)
• VI: Malignant (ROM ~99%)

Benign Nodule Management - Watchful Waiting Wins

• Follow-up (Bethesda II): USG surveillance; repeat 6-24 months, then less frequently if stable.
• Surgery indications:
  • Compressive symptoms.
  • Cosmetic concerns.
  • Patient preference.
  • Suspicious growth (>20% 2D / >50% vol).
  • Substernal extension.
• TSH Suppression: Limited role, not routine.

⭐ Asymptomatic, cytologically benign thyroid nodules (Bethesda II) are typically managed with serial ultrasound surveillance.

Thyroid Cancers Unmasked - Malignancy Map

• Differentiated Thyroid Cancers (DTC):
  • Papillary (PTC): Most common (~80%). Psammoma bodies, Orphan Annie eye nuclei. BRAF, RET/PTC. Lymphatic spread.
  • Follicular (FTC): ~10-15%. Capsular/vascular invasion defines malignancy. Hematogenous spread. RAS, PAX8-PPARγ.
  • Hürthle Cell: FTC variant, more aggressive.
• Medullary (MTC): ~5%. From C-cells. ↑ Calcitonin, ↑ CEA. MEN2A/2B (RET mutations).
• Anaplastic (ATC): <2%. Aggressive, elderly, dismal prognosis. TP53.
• Lymphoma: Rare, associated with Hashimoto’s thyroiditis.
• TNM Staging (AJCC 8th Ed - DTC): Key: T, N, M. Age (<55 yrs better prognosis) crucial.

⭐ Papillary thyroid carcinoma is the most common endocrine malignancy and often presents with cervical lymph node metastasis (📌 'Popular' cancer spreads to 'Popular' places - lymph nodes).

Cancer Combat Strategies - Treatment Tactics

• Surgery: Lobectomy or Total Thyroidectomy. Prophylactic CND (high-risk). Therapeutic Neck Dissection (nodal mets).
• Radioactive Iodine (RAI): For remnant ablation, adjuvant, or metastatic disease.
• TSH Suppression: Levothyroxine; target TSH usually <0.1-0.5 mU/L.
• EBRT/TKIs: For advanced, unresectable, or RAI-refractory (Lenvatinib, Sorafenib).
• Follow-up: Tg, Anti-Tg Ab, Neck USG, diagnostic RAI scan.

⭐ Serum Thyroglobulin (Tg) and anti-Tg antibodies are essential for monitoring recurrence in differentiated thyroid cancer post-thyroidectomy and RAI ablation.

High‑Yield Points - ⚡ Biggest Takeaways

• Papillary Thyroid Carcinoma (PTC) is the most common type; look for Orphan Annie eye nuclei and psammoma bodies.
• Medullary Thyroid Carcinoma (MTC) from C-cells secretes calcitonin; associated with MEN2/RET.
• Anaplastic carcinoma is highly aggressive, typically in the elderly with a dismal prognosis.
• Follicular carcinoma spreads hematogenously; capsular/vascular invasion is key for diagnosis.
• Fine Needle Aspiration (FNA) biopsy is the gold standard for evaluating suspicious thyroid nodules.
• Initial nodule workup includes TSH and thyroid ultrasound; cold nodules on scintigraphy are more suspicious for malignancy.
• Bethesda system is crucial for reporting thyroid cytopathology results from FNA.