|Year : 2012 | Volume
| Issue : 1 | Page : 1-2
Lymph node metastasis in papillary thyroid carcinoma: Making the fine-needle aspiration biopsy do even more
Ambika Gopalakrishnan Unnikrishnan, Rohini V Jayakumar, Binu P Pillai
Department of Endocrinology, Amrita Institute of Medical Sciences, Amrita VishwaVidya Peetham, Cochin, India
|Date of Web Publication||28-Jan-2012|
Ambika Gopalakrishnan Unnikrishnan
Professor, Department of Endocrinology, Amrita Institute of Medical Sciences, Amrita Viswa Vidya Peetham, Cochin
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Unnikrishnan AG, Jayakumar RV, Pillai BP. Lymph node metastasis in papillary thyroid carcinoma: Making the fine-needle aspiration biopsy do even more. Thyroid Res Pract 2012;9:1-2
|How to cite this URL:|
Unnikrishnan AG, Jayakumar RV, Pillai BP. Lymph node metastasis in papillary thyroid carcinoma: Making the fine-needle aspiration biopsy do even more. Thyroid Res Pract [serial online] 2012 [cited 2019 Dec 15];9:1-2. Available from: http://www.thetrp.net/text.asp?2012/9/1/1/92386
"Malignant changes frequently occur in these aberrant thyroids"
-Lazarus and Rosenthal, 1933. 
In subjects with newly diagnosed papillary thyroid cancer, it is important to detect lymph node metastasis, for staging, prognosis, and management planning. In subjects who are known to have had surgery for papillary thyroid cancer, the importance of detecting cervical lymph node metastasis becomes essential, for in this setting, the diagnosis could help in the timely treatment of a recurrence or residual disease. Fine-needle aspiration biopsy (FNAB) and ultrasound assessment are the most important tools for diagnosing cervical lymph node metastasis from papillary thyroid cancer. In order to supplement the results of these two useful tests, it has been suggested that measuring Thyroglobulin (TG) in the FNAB washout fluid could help in detecting lymph node metastasis from papillary thyroid carcinoma. The FNAB washout fluid is generally obtained by rinsing the aspirate remaining in the syringe and needle (in the post-FNAB setting) using normal saline. It has been suggested earlier that FNAB washout fluid be assessed for TG values, and that a TG value that is greater than 10 ng/ml be used as an indicator that the lymph node could be positive for cervical lymph node metastasis from papillary thyroid carcinoma. 
An interesting study published recently explores this work further.  This editorial is essentially a commentary on this study. In this paper, Sohn et al. attempt to improve upon the diagnostic accuracy of the FNAB-washout TG-analysis (hereafter termed FNAB-TG).  The authors argue that a careful study of subjects with the FNAB-TG values in the indeterminate range may help to improve diagnostic cut-offs for the same. In this study, the authors assessed ultrasound-guided FNAB followed by FNAB-TG assessments in suspicious-looking cervical lymph nodes in patients with papillary thyroid carcinoma, followed by thyroid surgery. The authors studied 95 lymph nodes in 92 subjects. The authors suggest that the FNAB-TG cut-off of 5 ng/ml provided a sensitivity of 69%, specificity of 83%, and an accuracy of about 76.8%.
This clinical study is important as it serves to further delineate an important clinical problem. In patients who have papillary thyroid carcinoma, and who have undergone surgery, long-term follow-up is essential. Such follow-up consists of whole body iodine scintigraphy, serum TG assessment (with a concomitant assessment of anti-TG antibodies), and finally, the ultrasound study of the neck to look for lymph node enlargement. Certain ultrasound features heighten the suspicion of metastasis in this setting: loss of fatty hilum, presence of a cystic change, a more echogenic image of the lymph node when compared with surrounding muscle tissues, a round (rather than oval) shape, and the presence of calcification. The suspicion often leads to an FNAB test, which may or may not be diagnostic. Thus, in many cases, the decision to operate becomes a clinical decision, based on the results of the ultrasound and FNAB, and also whether the serum TG levels are elevated. It is in this setting that the study by Sohn et al. assumes relevance as an elegant step in the search to achieve clarity in management.  Further studies should look prospectively at the utility of the FNAB-TG test, and its potential to alter management of these cases and its success in correctly predicting the nature of the node. It is important to note that the FNAB-TG is a supplementary test, and when used in addition to other clinical tools like the ultrasound report, the cytology findings and the FNAB level, add to assessing the comprehensive risk prediction of the patient having a cervical lymph node metastasis from a papillary thyroid carcinoma.
The issue of the cervical lymph node metastasis in papillary thyroid carcinoma has been long debated. Indeed, the beginnings of this debate may be traced to the year 1906, when Shrager first described the aberrant thyroid mass; this was followed by the proposal by Billings et al. in 1925 that these masses could be papillary in type; finally, in the 1930s, Lazarus and Rosenthal together opined that malignancy can frequently occur in these aberrant glands.  Well, even this concept has been questioned, with some authors suggesting that not all these so-called aberrant thyroids are malignant, and that they might represent ectopic thyroid tissue.  To add to all those continuing controversies about the cervical lymph node metastasis in papillary thyroid carcinoma comes the current issue: can we detect lymph node metastasis in a timely manner, in a post-thyroid surgery setting? The FNAB-TG level is an important step in this regard. In future, newer tests modeled on this method might prove useful. Alternatively, a combination of clinical and investigation-related risk factors may be compiled to develop a scoring system that might alert the clinician to a heightened suspicion of malignancy in this intriguing clinical scenario.
| References|| |
|1.||Lazarus JA, Rosenthal AA. Lateral Aberrant Thyroid Glands. Ann Surg 1933;98:1023-9. |
|2.||Kim MJ, Kim EK, Kim BM, Kwak JY, Lee EJ, Park CS, et al. Thyroglobulin measurement in fine-needle aspirate washouts: The criteria for neck node dissection for patients with thyroid cancer. Clin Endocrinol (Oxf) 2009;70:145-51. |
|3.||Sohn YM, Kim MJ, Kim EK, Kwak JY. Diagnostic performance of thyroglobulin value in indeterminate range in fine needle aspiration washout fluid from lymph nodes of thyroid cancer. Yonsei Med J 2012;53:126-31. |
|4.||Watson MG, Birchall JP, Soames JV. Is 'lateral aberrant thyroid' always metastatic tumour? J Laryngol Otol 1992;106:376-8. |