Dae Sik Kim, Presenter: Nothing to Disclose

Dong Gyu Na, Abstract Co-Author: Nothing to Disclose

‘FNA tract sign’ was defined as a linear hypoechoic needle tract transiently created by to and fro motion of a FNA needle during the FNA procedure. This study was performed to retrospectively determine if the ‘FNA tract sign’ is predictive of a benign follicular thyroid nodule.

FNA was performed for 3866 nodules of 2961 patients for 26 months. One experienced radiologist prospectively evaluated the presence of the FNA tract sign during each FNA procedure. This study included 102 (2.6%) nodules of 100 (3.4%) patients that showed FNA tract signs during FNA procedures. Final diagnoses of thyroid nodules were made by surgery for follicular neoplasm or malignancy and by at least two times of FNA or core-needle biopsy for benign thyroid nodules. We retrospectively evaluated US features of nodules and also assessed the FNA cytology results and final diagnoses of positive tract sign nodules. We evaluated the malignancy risk of positive tract sign nodules based on final diagnoses.

The FNA cytology results of 102 thyroid nodules with FNA tract signs were nondiagnositc 6 nodule (6%), benign 79 (77%), atypical of undetermined significance 13 (13%), and follicular neoplasm 4 (4%). The final diagnosis was made in 49 (48%) of 102 nodules; 48 benign nodules (nodular hyperplasia or benign follicular nodule 47, follicular adenoma 1) and one malignant nodule (minimally invasive follicular carcinoma). The initial FNA cytology results of finally diagnosed thyroid nodules with FNA tract signs were nodiagnostic 1 (2%), benign 43 (88%), AUS 4(8%), and follicular neoplasm 1 (2%). The most common sonographic feature of nodules with FNA tract sign nodules were solid (97%), ovoid to round shape (99%), well-defined smooth margin (71%), isoechogenicity (84%), absence of calcification (91%), central and peripheral vascularity (67%), hypoechoic halo (87%), and absence of spongiform appearance (96%). The malignant risk of nodules with FNA tract sign was 2%. The malignant risk of isoechoic nodules with FNA tract sign was 0% (0/45) and that of hypoechoic nodules with FNA tract sign was 25% (1/4).

FNA tract sign is highly predictive of a benign follicular nodule and isoechoic thyroid nodule with FNA tract sign may be considered as a benign follicular nodule.

Although FNA tract sign is uncommon, it will be helpful in the management of thyroid nodules.  

Kim, D, Na, D, FNA Tract Sign Is Highly Predictive of Benign Follicular Nodule.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043474.html