Background: In the diagnosis and follow-up of differentiated thyroid cancer (DTC) patients, a major clinical objective is to differentiate whether the cause of enlarged neck lymph nodes is either tumorous or inflammatory. High-frequency (7.5-10 MHz) ultrasound examination proved to be highly informative in this regard. An oval shape of the examined lymph node (longitudinal/anteroposterior diameter ratio, L/A > 1.5) and a central echogenic hilus indicate a benign lymphadenopathy. Roundness (L/A < or = 1.5), absence of the central echogenic hilus and a parenchymatous echogenicity are considered as signs of malignancy.
Methods: A series of 131 lymph nodes in DTC patients were examined at ultrasound and, on the basis of round shape (L/A < or = 1.5) in association with either one or both the other features (absence of central echogenic hilus, homogenous internal echo), 94 lymph nodes were classified a "malignant" and 37 "benign". The ultrasonographic diagnosis was evaluated with either cytologic or histologic diagnosis in all "malignant" nodes and in 7/30 "benign" nodes. In the other 30 "benign" nodes volume shrinkage or lymph node disappearance was observed during follow-up period.
Results: According to the results obtained, the ultrasound features utilized provided a good diagnostic accuracy (87%) with only 5 false positive case.
Conclusions: High-frequency sonography, therefore, must be considered a useful and accurate method for evaluating suspected lymphadenopathy in DTC patients.