Purpose or Case Report: To evaluate the diagnostic accuracy of US and the most useful sonographic features for diagnosing metastatic cervical adenopathy in pediatric patients with thyroid carcinoma
Methods & Materials: IRB-approved retrospective study in a tertiary children's hospital. Eligiblity for inclusion were all consecutive children with pathologically proven thyroid carcinoma from 2008 to 2017. Patients with no preoperative US or no resected lymph nodes were excluded. Pathology report of lymphadenopathy was used as the gold standard. Size, shape, echotexture and vascularity of the lymph nodes were analyzed and compared to the pathology findings
Results: We reviewed preoperative US and histology reports of resected lymph nodes in 52 children with proven thyroid carcinoma (33F,19M; age range 5-18y; mean 13y). Metastatic cervical lymph node disease was documented on US in 29 children and on histology in 33. Sensitivity of US was 79%, specificity 84%, PPV 90%, NPV 70% and accuracy 81%. A significant association was seen between round shape, echotexture, vascularity and lymph node histology. The measurements in short axis for the metastatic nodes was significantly higher than benign nodes (U=168.5,P=0.005, Mann-Whitney U test). No significant difference was noted between the groups in long axis. Logistic regression Univariate analysis showed that round shape (OR=0.054,95%CI=0.006–0.466), echotexture (OR=0.048,95%CI=0.01-0.234), vascularity (OR=0.025,95%CI=0.003–0.225) and short axis measurement (OR=1.473,95%CI=1.019–2.130) contribute significantly to make a positive diagnosis. Multiple logistic regression analysis showed only vascularity contributed significantly to explain the disease probability when adjusting for the other variables. Importantly, 11 patients (38% of children with metastatic disease documented on US) had US diagnosis of abnormal lymph nodes based solely on abnormal echogenicity and vascularity, with normal size and shape
Conclusions: Neck US showed high accuracy, sensitivity and specificity for identifying malignant adenopathy in children with thyroid carcinoma. Most of the abnormal lymph nodes were round in shape and had abnormal echogenicity and vascularity. However, this paper emphasizes that metastatic nodes may be normal in size and shape and the abnormality may be based solely on abnormal echogenicity and vascularity. Size, particularly long axis measurement, is not a reliable criterion to differentiate between malignant and benign lymph nodes. This has not been reported previously in pediatrics