EUS-FNA and FDG-PET are complementary procedures in the diagnosis of enlarged mediastinal lymph nodes

Background and Study aims : Transoesophageal endosonography with fine needle aspiration (EUS-FNA) and 2-deoxy-2-[fluorine- 18]fluoro-D-glucose positron emission tomography (FDG-PET) are now standard diagnostic procedures of the mediastinum. Our aim was to compare their value in the assessment of enlarged mediasti- nal lymph nodes detected by computed tomography. Patients and methods : Forty consecutive patients with a suspi- cion of cancer or a history of pulmonary, digestive, urogenital or mammary neoplasia and presenting with supracentimetric lymph nodes on computed tomography underwent whole body FDG-PET and EUS-FNA. Final diagnosis of malignancy was obtained by cytology, surgery or long-term follow-up. Results : EUS-FNA showed a sensitivity, specificity and accura- cy for detection of malignancy of 79.3, 100 and 85%, respectively. The biopsy material was adequate for cytological examination in 37 patients. Sensitivity, specificity and accuracy of PET were 100, 54.5 and 87.5%, respectively. FDG-PET correctly diagnosed the primary site in 27 patients, and showed additional unknown extrathoracic metastatic sites in 15 patients. The five false positive results observed with FDG-PET consisted in a final diagnosis of sarcoidosis, tuberculosis, anthracosilicosis and reactive lymph nodes, respectively. The association of FDG-PET and EUS-FNA avoided more invasive procedures (mediastinoscopies or staging surgery) in 34 patients. Conclusions : EUS-FNA and FDG-PET are complementary diagnostic procedures combining the high sensitivity of FDG-PET and the high specificity of EUS-FNA to accurately diagnose malig- nancy in enlarged mediastinal lymph nodes identified by CTscan. The combination of the two procedures in selected cases with pul- monary cancer or extra-thoracic tumours avoided more invasive diagnostic and surgical procedures. (Acta gastroenterol. belg., 2008, 71, 219-229).