Association of a Number of Tumor Foci with Ultrasound Patterns and Reoperation Rate in Well-Differentiated Thyroid Cancer (WDTC)-A Single-Center Analysis.

[BACKGROUND] Suspicious ultrasound patterns are essential for the accurate preoperative assessment of thyroid cancer (TC). The number of tumor foci may serve as an additional parameter, particularly when considered in association with ultrasound patterns and the reoperation rate.

[METHODS] We conducted a retrospective analysis of 665 well-differentiated TC (WDTC) patients treated between 2008 and 2024. The analysis included preoperative data, ultrasound patterns (hypoechogenicity, microcalcifications, high vascularity, and irregular tumor shape or margins), and histopathological findings regarding the number of tumor foci and reoperation rates, additionally stratified by TNM stage and sex.

[RESULTS] A statistically significant association was observed between the number of tumor foci and the mean number of ultrasound patterns ( < 0.05). The highest mean number of patterns was found with ≥4 foci (SD: 2.50 ± 1.20). However, this relationship was not linear, as in each focus category (1, 2, 3, and ≥4), the greatest number of ultrasound patterns consistently predominated. No significant association was found between a higher number of foci and a complete set of ultrasound patterns ( = 0.273) or the reoperation rate ( = 0.469). Analyses stratified by TNM stage and sex also did not reveal any significant differences ( > 0.05).

[CONCLUSIONS] Although the number of tumor foci demonstrates an association with ultrasound patterns, the lack of a consistent linear correlation and the absence of an impact on reoperation rates suggest that this parameter may provide limited additional clinical value beyond the general concept of multifocality.