Biopsy of Tiny Thyroid Nodules: Not a Question of “Can We” but “Should We”

We read with great interest the case report by Kim et al,¹ describing the successful sonography-guided biopsy of a 1-mm papillary thyroid microcarcinoma (PTMC). The superficial location of the thyroid gland and generally favorable conspicuity of lesions makes sonography-guided biopsy of thyroid nodules a safe and straightforward procedure in experienced hands. The benefit of obtaining the diagnosis of PTMC in such a small nodule, however, should be weighed against the risk and cost of negative and nondiagnostic fine-needle aspiration biopsy and subsequent work-ups, given the high frequency of incidental subcentimeter thyroid nodules in the general population. High-resolution-sonography examination detects thyroid nodules in up to 67% of randomly selected individuals,² and a significant number of individuals who die of other causes have thyroid cancers incidentally discovered at postmortem,³ indicating that many small nodules will not be clinically significant even if they represent PTMC.

The fact that the patient underwent thyroid sonography despite any pertinent risk factors for thyroid malignancy, thyroid function laboratory abnormalities, or palpable abnormality of the thyroid gland or elsewhere in the neck underscores the problems with initiating the sequence of overdiagnosis and overtreatment. The latest American Thyroid Association guidelines⁴ state that “given unfavorable cost/benefit considerations, attempts to diagnose and treat all small thyroid cancers in an effort to prevent these rare [unfavorable] outcomes would likely cause more harm than good,” and they recommend biopsy only for nodules >10 mm.

The management of the patient in this case was affected by the diagnosis of the contralateral PTMC, and a total thyroidectomy was performed instead of a hemithyroidectomy. In the study by Roti et al,⁵ even with a high prevalence of incidentally found bilateral or multifocal cancers in thyroidectomy specimens, most were histologically PTMC and only rarely more aggressive types. Hay et al⁶ studied 535 patients with PTMC during a mean of 16 years and determined that the mortality rate was 0.4% and the 20-year recurrence rate was 6%. Therefore, it is even controversial whether detection, diagnosis, or resection of the contralateral 1-mm PTMC would have affected the patient's long-term morbidity and mortality. While it is certainly technically feasible to biopsy tiny thyroid nodules as small as 1 mm, it is not of proved benefit to do so routinely either from a cost-effectiveness or clinical outcome standpoint. Limiting initial overdiagnosis coupled with periodic sonographic and clinical evaluation for growth and change in imaging characteristics remains the best current approach for management of tiny thyroid nodules.

Finally, the patient's presenting complaints of “fatigue and neck discomfort” were undoubtedly not related to the small PTMC, and one wonders if these symptoms have resolved.

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