Natural History of Benign Thyroid Nodules

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 471-496-Thyroid Neoplasia & Case Reports
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-481
Won Chul Ha*, Su Jin Oh, Ha Neul Park, Bo Kyung Kim, Yeon Ji Kim, Woo Ho Ban, Hong Seok Lee, Hyun Shik Son and Tae Seo Sohn
Uijeongbu St. Mary's Hospital, Uijeongbu, South Korea
Thyroid nodules are present in nearly 50% of adults, and increasing in prevalence with age. It is recommended that all benign thyroid nodules be followed with serial US examinations 6-18 months after initial FNA. Nodule growth is not in and of itself pathognomonic of malignancy, but growth is an indication for repeat biopsy. The aim of this study is to determine the natural history of cytologically benign thyroid nodules by ultrasonography (US).

We retrospectively reviewed 168 patients (13 males, 155 females) who had thyroid nodules with benign cytologic results by US-guided fine needle aspiration (FNA) on the initial visit and follow-up US within the 5-year period. Thyroid nodules were classified as solid, less than 50% cystic and more than 50% cystic nodules. Nodule growth is defined as increase in nodule diameter with a minimum increase in two or more dimensions of at least 2 mm.

The patients with 55.3 ± 11.4 year-old had baseline TSH 1.54 ± 0.96 mIU/L and nodules with maximal diameter 1.51 ± 0.84 cm. 79.2% nodules were solid, 13.1% less than 50% cystic, and 7.7% more than 50% cystic. Of the 168 nodules, 43.5% nodules grew over 4.01 ± 1.53 years, 50% nodules were no size change over 5.1 ± 2.85 years, and 6.5% nodules decreased over 4.0 ± 2.58 years. Of the growing nodules, 68.5% was solid, 28.8% less than 50% cystic, and 2.7% more than 50% cystic nodules. Of the nodules without size change, 86.9% nodules were solid and 9.5% nodules were less than cystic nodules.

39% nodules of all solid nodules, 72% nodules of all less than 50% cystic nodules, and 20% nodules of all more than 50% cystic nodules grew over time. The patients with growing nodules were younger compared with those with nodules without size change and decreasing nodules (53.4 ± 12.1 vs 59.6 ± 6.8 and 56.4 ± 11.2 years old). Only 1 (0.60%) of 168 initially benign nodules was malignant during follow up. Baseline TSH level and nodule size were not associated with nodule growth during follow up period.

Not all benign solid nodules grow and 2/3 of less than 50% cystic nodules grow over time. Younger age is associated with nodule growth and nodule growth is not a reliable predictor of malignancy

Nothing to Disclose: WCH, SJO, HNP, BKK, YJK, WHB, HSL, HSS, TSS

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