Is completion thyroidectomy medically necessary for a patient with a history of right-sided thyroid follicular cancer (IS 60260) who underwent right-sided thyroid lobectomy?

Completion Thyroidectomy is NOT Medically Necessary for This Patient

For a patient with a 3.5 cm minimally invasive follicular carcinoma with no lymphovascular invasion, no capsular invasion beyond minimal, no contralateral nodules, and unremarkable surveillance imaging, completion thyroidectomy is not indicated and active surveillance is the appropriate management strategy. 1

Risk Stratification

This patient's follicular carcinoma meets low-risk criteria:

• Tumor size 3.5 cm (≤4 cm threshold) 1
• Minimal capsular invasion only, no extrathyroidal extension 1
• No lymphovascular invasion 1
• No cervical lymph node metastases (normal ultrasound and laryngoscopy) 1
• No contralateral nodules (unilateral disease) 1
• No distant metastases 1

The NCCN mandates completion thyroidectomy only when high-risk features are present: tumor >4 cm, extrathyroidal extension, cervical lymph node metastases, distant metastases, poorly differentiated histology, or bilateral nodularity—none of which apply to this case. 1

Surgical Risk-Benefit Analysis

The risks of completion thyroidectomy outweigh any potential benefits in this low-risk scenario:

• Recurrent laryngeal nerve injury risk: 2.5% 1
• Permanent hypoparathyroidism risk: 8.1% 1
• No survival benefit demonstrated for low-risk follicular carcinoma with lobectomy alone 1

Unlike papillary thyroid carcinoma where bilateral nodularity mandates total thyroidectomy regardless of other features 2, 3, this patient has no contralateral nodules, eliminating this indication.

Thyroglobulin Monitoring After Lobectomy

The concern about inability to follow thyroglobulin levels with residual thyroid tissue is addressed by current guidelines:

• Thyroglobulin can be reliably monitored after lobectomy by following trends over time rather than absolute values 4
• Rising thyroglobulin levels are highly suspicious for persistent/recurrent disease and should prompt imaging 4
• For patients with lobectomy alone, thyroglobulin <30 ng/mL defines low-risk status 4
• The trend of basal thyroglobulin should be used in patients with residual thyroid tissue 4

The NCCN recommends thyroglobulin measurement at 6-12 weeks postoperatively and ongoing surveillance with periodic measurements after lobectomy for appropriate low-risk disease. 1

Recommended Management Strategy

Active surveillance is the appropriate approach:

• Continue levothyroxine therapy to maintain TSH in low-normal range (0.5-2 μIU/mL) 4
• Measure serum thyroglobulin every 6-12 months 4, 1
• Perform neck ultrasound every 6-12 months initially 4
• Reserve completion thyroidectomy for suspicious findings on surveillance imaging 1

Follicular Carcinoma-Specific Considerations

While follicular carcinoma spreads hematogenously rather than lymphatically 4, this patient's minimal invasion and absence of lymphovascular invasion place him at very low risk for distant metastases. The normal ultrasound excludes thyroid bed recurrence, and the absence of contralateral nodules eliminates concern for synchronous disease.

When Completion Thyroidectomy Would Be Indicated

Completion thyroidectomy should be reserved for:

• Development of suspicious findings on surveillance ultrasound 1
• Rising thyroglobulin levels suggesting recurrence 4
• Discovery of contralateral nodules requiring evaluation 2
• Presence of any high-risk features not initially identified 1