A Simple Categorizing System for the Management of Incidental Thyroid Nodules and Autoimmune Thyroid Disease Detected on Computed Tomography

Program: Abstracts - Orals, Poster Previews, and Posters
Session: SAT 270-310-Thyroid Neoplasia (posters)
Saturday, April 2, 2016: 1:15 PM-3:15 PM
Exhibit/Poster Hall (BCEC)

Poster Board SAT 270
Shoichiro Izawa*, Kazuhisa Matsumoto, Kazuhiko Matsuzawa, Hiroko Ohkura, Kyoko Shoji, Risa Nakanishi, Keisuke Sumi, Youhei Fujioka, Tsuyoshi Ohkura, Masahiko Kato, Shin-ichi Taniguchi and Kazuhiro Yamamoto
Tottori University Faculty of Medicine, Yonago, Japan
Background: Incidental thyroid nodules (ITN) and diffuse goiter were often detected on computed tomography (CT). Their prevalence was more than 16% in the situation of managing unrelated health conditions, though only 9 to 11% of them were malignancy. However, no typical findings on CT were reported for distinguishing thyroid lesions. Current management guidelines for thyroid nodules recommended that all ITN should be evaluated by ultrasound (US). If the nodules evaluated by US were suspected of malignancy, fine-needle aspiration biopsy (FNAB) was also recommended. The objective of our study was to explore the abnormal findings on CT associated with thyroid nodules, papillary thyroid carcinoma, and autoimmune thyroid disease (AITD).

Patients and Methods: This retrospective analysis included patients who were pointed out ITN or diffuse goiter on CT from October, 2011 to September, 2014. Patients with the history of thyroid disease were excluded. Their findings were reviewed by radiologists and categorized into 4 groups (Group 1: low density area with diffuse goiter, Group 2: low density area without diffuse goiter, Group 3: multiple nodules, and Group 4: single nodule). They were consulted to endocrinologists and evaluated by thyroid function test (TSH and Free T4), serum thyroglobulin (Tg), thyroid autoantibodies (TgAb and TPOAb), and US. If the nodules were suspected of malignancy by US, FNAB was also applied.

Results: A total of 123 (40 male and 83 female) patients, mean age 66.6±12.5 years old, was enrolled. Twenty of 123 (12.3%) patients were categorized in Group 1, and 14 of 123 (11.4%) were in Group 2. As to nodular lesions, 22 of 123 (17.9 %) were categorized in Group 3, and 67 of 123 (54.5 %) were in Group 4. No significant differences among the groups were observed in thyroid function test, Tg, positive ratio of thyroid autoantibodies, number of nodules, and largest diameter of maximum nodule. The incidence of AITD in Group 1 (12/20) and 2 (4/14) were significantly higher (p <0.05) than that of Group 3 (2/22) and 4 (7/67). Also, the incidence of adenomatous lesions in Group 3 (18/22) was significantly higher (p <0.05) than that of Group 1 (8/20), 2 (8/14), and 4 (35/67). Eight papillary thyroid carcinomas (one in Group 3 and 7 in Group 4) were diagnosed by FNAB, though the incidence was not significantly different among the groups.

Conclusions: More than 70% of incidentally detected thyroid findings on CT were nodular lesions, which were associated with adenomatous lesions. On the other hand, low density area was associated with AITD. Nodular lesions on CT were simple and effective parameter to stratify the risk of thyroid nodule including malignancy.

Nothing to Disclose: SI, KM, KM, HO, KS, RN, KS, YF, TO, MK, SIT, KY

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