The role of ultrasound and ultrasound-guided fine needle aspiration biopsy of lymph nodes in patients with skin tumours
Objectives The primary objective of this study is to evaluate US diagnostic accuracy in the study of superficial lymph nodes, during the follow-up of patients surgically treated for skin tumours. The secondary objective is to compare the positive cytological results with the histological report.
Methods From 2004 to 2011, 480 patients (M/F: 285/195; median age: 57 years; prevalent histotype: melanoma) underwent ultrasound-guided FNA of suspicious for recurrence lymph node. An expert radiologist performed US test of the lymph nodes, expressing either negative or positive report to the test, and then ultrasound-guided FNA examination. The FNA positive patients were subjected to lymphadenoctomy; the patients who tested negative were subjected to follow-up.
Results The lymph node dimensions were ≤ 2 cm in 90% of cases. Out of the 336 (70%) US “positive” patients, 231 were FNA positives; out of the 144 (30%) US “negatives”, 132 (91.7%) were FNA negatives; the sensitivity and specificity of the US were to 95% and 55.7%, respectively; the negative predictive value was 91.7% and the positive predictive value was 68.8%. In 97.5% of lymphadenoctomies the definitive histology has confirmed FNA positivity.
Conclusions Ultrasound is a sensitive method in the evaluation of superficial lymph nodes in the follow-up of patients with skin tumours; the false negatives are attributable to micro-metastases or partial colonizations. In the lymph nodes of smaller size the differential diagnosis between the structural alteration by phlogosis and the tumour is by no means easy (55.7% specificity). The elevated positive predictivity of cytology has been confirmed.