Papillary Thyroid Carcinoma

🩺 Papillary Thyroid Carcinoma

📌 Definition & Key Facts

Papillary carcinoma arises from follicular epithelial cells and characterized histologically by papillary structures with fibrovascular cores.

• Peak incidence: 3rd–4th decades
• Sex ratio: Female : Male ≈ 3 : 1
• Prognosis: Excellent (especially in younger patients)

What is the most common thyroid cancer?

What is the most common pediatric thyroid malignancy?

⚠️ Risk Factors of Papillary Thyroid Carcinoma

• Ionizing radiation to head/neck (especially childhood exposure)

• Iodine status: More common in iodine-sufficient areas

• Family history (5–10% familial cases)

Which genetic alterations are commonly associated with Papillary Thyroid Carcinoma?

What Familial syndromes are associated with Papillary Thyroid Carcinoma?

🧾 Clinical Features of Papillary Thyroid Carcinoma

• Often asymptomatic thyroid nodule (firm, non-tender)

• Multifocality common (~up to 80% multicentric) — can involve both lobes

• Cervical lymph node metastasis common (~30% clinically) — nodal disease more common than distant spread

• Local invasion → hoarseness (RLN), dysphagia (esophagus), dyspnea (trachea)

• Distant metastasis (less common)

• In iodine-deficient areas: may present with multinodular goiter; in iodine-replete areas: solitary nodule more common

Which are the common sites for distant metastasis in Papillary Thyroid Carcinoma?

🔬 Gross Pathology of Papillary Thyroid Carcinoma

• Solid granular cut surface with irregular outline
• Often cystic changes, colloid, gritty/friable areas

🧪 Histology of Papillary Thyroid Carcinoma

Principal defining features are nuclear changes rather than cytoplasmic architecture:

• Papillae with fibrovascular cores (glandular cells on a stalk)
• Orphan Annie eye nuclei
• Nuclear grooves (longitudinal; “coffee-bean” appearance)
• Intranuclear cytoplasmic inclusions (pseudo-inclusions)
• Psammoma bodies — seen in ~50%
• Nuclear crowding / overlap (“stacked eggs” appearance)

What are Orphan Annie nuclei?

What are Psammoma bodies?

🧩 Histologic Variants of Papillary Thyroid Carcinoma

• Follicular variant
• Microcarcinoma — ≤1 cm (excellent prognosis)
• Diffuse sclerosing variant
• Tall cell variant
• Columnar / solid variants

🧭 Investigations of Papillary Thyroid Carcinoma

• Ultrasound (first-line)

• FNAC (US-guided): Diagnostic method of choice (Bethesda reporting)

• Thyroid function tests: Usually euthyroid; assess baseline pre-op

• Cross-sectional imaging (CT/MRI)

• Chest X-ray / CT chest: If pulmonary metastasis suspected

• Molecular testing (BRAF, RET/PTC, RAS) may guide prognosis/therapy in select cases

Name 4 ultrasound features strongly suspicious for papillary carcinoma.

What is the purpose of CT/ MRI Scan in Papillary Thyroid Carcinoma?

🛠️ Treatment of Papillary Thyroid Carcinoma

Primary modality: Surgery ± adjuvant therapy, individualized by risk.

1. Surgery

• Hemithyroidectomy / lobectomy: acceptable for small (≤1 cm), unifocal, intrathyroidal tumors without nodes or high-risk features.

• Total thyroidectomy

What are the indications of Total Thyroidectomy in Papillary Thyroid Carcinoma?

• Neck dissection:

  • Central compartment (level VI) dissection for clinical/ radiologic positive nodes or high-risk tumors (≥4 cm, extrathyroidal extension, aggressive histology).

  • Therapeutic lateral neck dissection only if overt lateral node disease; prophylactic lateral dissection is not routinely beneficial.

2. Radioiodine (I-131) Ablation

• Post-op ablation after total thyroidectomy

What are the indications of Radioiodine ablation in Papillary Thyroid Carcinoma?

When is Radioiodine ablation done after total thyroidectomy?

3. Thyroid Hormone Suppression

• Levothyroxine to suppress TSH (TSH stimulates follicular cells)

What is the level of TSH to aim for post Total Thyroidectomy?

4. External Beam Radiotherapy (EBRT)

• Reserved for unresectable local disease, gross residual disease not iodine-avid, or palliation (IMRT preferred)

5. Systemic / targeted therapy

• For progressive metastatic or RAI-refractory disease (tyrosine kinase inhibitors etc.) — specialist decision

📈 Treatment Response & Follow-up of Papillary Thyroid Carcinoma

Assessment tools

• Post-ablation scan (2–10 days after I-131) — evaluate residual uptake / metastasis

• Serum thyroglobulin (Tg) — tumor marker for differentiated thyroid cancer (most sensitive when stimulated)

• Neck ultrasound — routine surveillance for local/ nodal recurrence

• Cross-sectional imaging / PET-CT — if Tg elevated but imaging negative or for iodine-refractory disease

What are the different response categories while assessing treatment outcome in Papillary Thyroid carcinoma? What is the follow up protocol in each group?

What Tg value is highly predictive of persistent disease?

📉 Prognosis of Papillary Thyroid Carcinoma

• Overall excellent prognosis: 10-year survival ~90% if thyroid-confined; ~60% with extrathyroidal spread

What are poor prognostic factors in Papillary Thyroid Carcinoma?