Papillary Thyroid Microcarcinoma: Is Active Surveillance Always Enough?

Rosie Sutherland; Venessa Tsang; Roderick J. Clifton-Bligh; Matti L. Gild

Disclosures

Clin Endocrinol. 2021;95(6):811-817. 

In This Article

Conclusion

While the majority of the recent increase in PTC incidence is attributed to overdiagnosis of PTMC, there remains a cohort of patients who require more nuanced risk stratification. Although most PTMCs behave in an indolent fashion, the small subset that behaves aggressively is not yet genomically or radiologically defined. While there is conflicting evidence regarding potential risk factors for disease progression, large groups in Japan and at Memorial Sloan Kettering Cancer Centre have demonstrated the safety and efficacy of active surveillance and have proposed risk stratification which can help to select appropriate patients. As the pendulum of treatment continues to swing towards conservative management, future research is required to clarify the natural history of all PTMCs and identify prognostic features among wider populations.

Case Example 1

An 80-year-old female is noted to have a thyroid nodule 7 mm in diameter during a carotid artery Doppler US for investigation of a suspected transient ischaemic attack. The patient is asymptomatic and there is no palpable mass or lymphadenopathy on examination. Her past medical history includes ischaemic heart disease and hypertension which is controlled with an ACE inhibitor. Thyroid US shows a solitary, isoechoic nodule within the right lobe of the thyroid; it has well-defined margins and poor vascular supply, with a rim of normal thyroid parenchyma separating the nodule from surrounding structures. There is no evidence of extrathyroidal extension or lymph node involvement on examination or US. Thyroid function tests are within normal ranges.

Approach: Active surveillance would be appropriate in this case. The nodule has a low risk of progression given its size (≤10 mm in diameter) and absence of suspicious features on US including evidence of lymph node involvement or extrathyroidal extension. Other factors favouring active surveillance in this case include the patient's age and comorbidities. FNAB is therefore not necessary in this instance.

Case Example 2

A 40-year-old female presents with a small, palpable neck lump. Thyroid US confirms a solid hypoechoic thyroid nodule 9 mm in diameter. The patient is clinically euthyroid and there is no evidence of extrathyroidal extension, lymph node involvement or distant metastasis on physical examination or US. There is no personal or family history of thyroid pathology and no significant past medical history. The nodule has an irregular, microlobulated margin with microcalcifications on US sonography without evidence of increased vascularity or close proximity to the RLN or trachea. Thyroid function tests are within normal ranges.

Approach: This patient has some suspicious features on US (irregular margin and microcalcifications) and her younger age may increase the risk of disease progression. However, there is no clinical or radiological evidence of lymphatic or metastatic spread. Given the low rates of disease progression for thyroid nodules ≤10 mm without evidence of extrathyroidal extension, lymph node involvement or distant metastasis, active surveillance could be offered in this case if it aligned with patient preference. FNAB could therefore be delayed and the patient should have a repeat thyroid US in 6 months.

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