갑상선 전절제 수술 후 초음파 소견
2023-01-31 10:33:53
Lymph nodes with an echogenic centre are typically benign, as are oval or cylindrical nodes.(1) The echogenic centre represents the fatty hilum. Normal nodes and reactive hyperplastic nodes are characterised by an elongated shape and a well-defined echogenic hilum, which is continuous with the adjacent fat (Figs. 5a & 6a). Power Doppler shows vascularity entering the centre or hilum of the node, and extending toward each tip (Figs. 5b & 6b). In smaller nodes, an echogenic fatty hilum may not be identifiable, especially in those that measure less than 5 mm. These small elongated nodes are commonly encountered in clinical practice and can be assumed to be benign (Fig. 7).
Metastatic nodes are usually hypoechoic (Fig. 8). However, metastatic nodes from PTCs tend to be hyperechoic (Fig. 10a). This is due to the deposition of Tg.(17) Also, the rounder the node, the greater the risk of involvement (Figs. 8 & 10a).(1) While nodal calcification is generally rare in metastatic nodes, it is common in metastatic nodes from PTCs (Figs. 10a & b).(17)
Lymph nodes showing peripheral vascularity that does not arise from the hilar vessels, or a combination of peripheral and hilar vascularity, are highly suspicious for malignancy (Figs. 11 & 12b). These peripheral or capsular vessels are recruited in response to pro-angiogenesis factors released by tumour cells.(17) Thus, signs of malignant adenopathy include the presence of internal calcification, a combination of peripheral and hilar vascularity (an almost certain sign of recurrent papillary cancer) (Figs. 11 & 12b), cystic or partially cystic nodes (Fig. 12a) and echogenic nodes.(1)
Recognition of advanced nodal disease with local infiltration of adjacent structures cannot be missed, as shown in Fig. 13. In a patient with PTC, the longitudinal US image shows an echogenic mass within the lumen of the right internal jugular vein (Fig. 13a), while the correlative computed tomography image confirms the infiltration of the right internal jugular vein by adjacent metastatic lymph node (Fig. 13b). Tumour recurrence in the right thyroid bed is also noted. Among the features described, Leboulleux et al reported the specificities for malignancy to be 100% for cystic appearance and punctate calcifications, although the corresponding sensitivity values were low (46% and 11%, respectively).(18) In the same study, the US feature that gave the best sensitivity-specificity compromise (86% and 82%, respectively) was the pattern of intranodal vascularisation.
