EUS-guided tissue acquisition in the study of the adrenal glands: Results of a nationwide multicenter study.

Background: There are limited data about the role of endoscopic ultrasound-guided tissue acquisition (EUS-TA), by fine needle aspiration (EUS-FNA) or biopsy (EUS-FNB), in the evaluation of the adrenal glands (AG). The primary aim was to assess the diagnostic yield and safety. The secondary aims were the malignancy predictors, and to create a predictive model of malignancy.

Methods: This was a retrospective nationwide study involving all Spanish hospitals experienced in EUS-TA of AGs. Inclusion period was from April-2003 to April-2016. Inclusion criteria: all consecutive cases that underwent EUS-TA of AGs. EUS and cytopathology findings were evaluated. Statistical analyses: diagnostic accuracy of echoendoscopist's suspicion using cytology by EUS-TA, as gold standard; multivariate logistic regression model to predict tumor malignancy.

Results: A total of 204 EUS-TA of AGs were evaluated. Primary tumor locations were lung70%, others19%, and unknown11%. AG samples were adequate for cytological diagnosis in 91%, and confirmed malignancy in 60%. Diagnostic accuracy of the endosonographer's suspicion was 68%. The most common technique was: a 22-G (65%) and cytological needle (75%) with suction-syringe (66%). No serious adverse events were described. The variables most associated with malignancy were size>30mm (OR2.27; 95%CI, 1.16-4.05), heterogeneous echo-pattern (OR2.11; 95%CI, 1.1-3.9), variegated AG shape (OR2.46; 95%CI, 1-6.24), and endosonographer suspicion (OR17.46; 95%CI, 6.2-58.5). The best variables for a predictive multivariate logistic model of malignancy were age, sex, echo-pattern, and AG-shape.

Conclusions: EUS-TA of the AGs is a safe, minimally invasive procedure, allowing an excellent diagnostic yield. These results suggest the possibility of developing a pre-EUS procedure predictive malignancy model.