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

Letters to the Editor Letters to the Editor

Published ahead of print on November 11, 2010
doi: 10.3174/ajnr.A2293

American Journal of Neuroradiology 32:E19, January 2011
© 2011 American Society of Neuroradiology

A.M. Saindanea and P.A. Hudginsa
aDepartment of Radiology
Emory University School of Medicine
Atlanta, Georgia

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 andnondiagnostic 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.

References

  1. Kim DW, Kim SH, Jung SJ. Successful sonography-guided fine-needle aspiration of a 1-millimeter-diameter papillary thyroid microcarcinoma. AJNR Am J Neuroradiol 2010;31:1082–84[Abstract/Free Full Text]
  2. Tan GH, Gharib H. Thyroid incidentalomas: management approaches to nonpalpable nodules discovered incidentally on thyroid imaging. Ann Intern Med 1997;126:226–31[Abstract/Free Full Text]
  3. Mortensen JD, Woolner LB, Bennett WA. Gross and microscopic findings in clinically normal thyroid glands. J Clin Endocrinol Metab 1955;15:1270–80[Abstract/Free Full Text]
  4. Cooper DS, Doherty GM, Haugen BR, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 2009;11:1167–214
  5. Roti E, Rossi R, Tranforini G, et al. Clinical and histological characteristics of papillary thyroid microcarcinoma: results of retrospective study in 243 patients. J Clin Endocrinol Metab 2006;91:2171–78[Abstract/Free Full Text]
  6. Hay ID, Grant CS, van Heerden JA, et al. Papillary thyroid microcarcinoma: a study of 535 cases observed in a 50-year period. Surgery 1992;112:1139–46[Medline]

Reply

Published ahead of print on November 11, 2010
doi: 10.3174/ajnr.A2294

American Journal of Neuroradiology 32:E20, January 2011
© 2011 American Society of Neuroradiology

D.W Kima, S.H. Kima and S.J. Junga
aBusan Paik Hospital
Inje University College of Medicine
Busan, South Korea

We are sorry to reply negatively. We do not believe that a reply is warranted because our article is only a case report and the letter is thought to be an overreaction.

In addition, Korean radiologists use a different size criterion (>5 mm in the largest diameter) in sonographic fine-needle aspiration biopsy of thyroid nodules unlike the American Thyroid Association guidelines (>10 mm).

Thank you for your interest.

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