Ultrasonographic punctate echogenic foci in metastatic lymph nodes and their presence in primary thyroid cancer

It is important to identify the origin of ultrasonographic punctate echogenic foci (PEF), which represent microcalcifications, in cervical lymph nodes (LNs). This study aimed to explore the malignancy rate of LNs with PEF and investigate its association with their presence in primary thyroid cancer. This retrospective study included 315 LNs of patients who underwent US-guided fine-needle aspiration at a tertiary hospital in 2019. The LN with PEF group showed a significant association between PEF in primary thyroid cancer and malignancy in LNs (P < .0001, odds ratio = 50.63, 95% confidence interval 10.6-241.75). In the group of LNs without PEF, no such significant association was observed (P = .7574, odd ratio = 0.89, 95% confidence interval 0.44-1.82). PEF in benign LNs were misrecognized as an echogenic hilum or a single hyperechoic spot. Benign lymphadenitis produced PEF in LNs. Cervical metastatic LNs with ultrasonographic PEF harbor PEF in primary thyroid cancer. In primary thyroid tumors without PEF, LNs with PEF are benign or associated with a nonthyroidal origin.