PURPOSE: To analyze the ultrasound (US) findings of newly diagnosed papillary thyroid cancers (PTCs) that were identified in following screening US
MATERIALS AND METHODS: During 4-year-period, we found 34 newly diagnosed PTCs in 32 patients who had previous US examinations, in that thyroid nodules were not detected or did not have suspicious findings. We divided them into two groups:newly detected thyroid nodules (NDTN), in which newly diagnosed PTCs were not detected on previous US and pre-existing thyroid nodules (PETN), in which the pre-existing nodule had some changes in the findings or the impression on following US. We investigated the interval between previous and following US examinations and the most frequent US findings that led to the diagnosis of PTCs.
RESULTS: Mean size of 34 newly diagnosed PTCs was 6.3 mm (range; 3-13 mm). Among them, NDTN was 20, and PETN was 14. The interval for NDTN and PETN was 33.7 months (range; 5 – 106 months) and 40.1 months (range; 6-116 months), respectively. NDTN less than a year (n=5) often occurred near preexisting large benign mass in 3 cases. NDTN after a year (n = 15) often had the factors prone to miss (n=9); superior pole or isthmus in 4, iso or mildly hypoechogenicity in 2, < 3 mm in size in 2, pre-existing benign mass in 1 and six were true new detection without the factors prone to miss. In PETN, the changes in next US findings were decrease in echogenicity (n = 4), minimal increase in size less than 5mm (n = 3) and the rest 7 did not show any change on US findings. Of the 7 lesions without changes, the impression of US examiners was changed, and previous and following examinations were performed by different US examiners in 6 of 7. Five cases (25%) of NDTN and 4 cases (21%) of PETN had metastatic lymph nodes in central neck or ipsilateral lateral neck. True new detection and size changes were not made in 16 months.
CONCLUSION: Newly diagnosed PTCs on following US are usually missed cancers due to undetection and misinterpretation. These lesions tend to show no or minimal growing even until 8 years. In thyroid US with benign assessment, frequent follow-up US may be unnecessary.
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SS 07 TH-04.pdf
