The Value Of Endoscopic Ultrasound In The Diagnosis Of Unknown Original Mediastinal Masses

Background and aims:Mediastinal masses, mainly maligant and inflammatory mediastinal adenopathy are common. Endoscopic Ultrasound (EUS) is widely used for the differential diagnosis. However, useful echofeatures that are specific for malignant mediastinal mass are still unclear, especially in high tuberculosis prevalence regions like China. This study aim to evaluate the efficacy of mediastinal mass echofeatures and FNA in the evaluation of benign and malignant mediastinal masses.Method:A total of 123 patients who underwent EUS for mediastinal mass evaluation were included, Echofeatures of mediastinal masses including size, echogenicity, margins, shape and elastography images were collected. Final dignosis was determined by surgical pathology, EUS-FNA or long-term follow-up.Results:There were 74 malignant cases among all 123 patients. Malignant mediastinal mass of EUS imaging features appear in the boundary, echo homogenization, cystic, blood vessels and infiltration of surrounding tissues compared with benign mediastinal mass, the difference was statistically significant (P<0.05). However, the median of long axis in malignant masses was not longer than that of benign cases. Roughly 1/3 of mediastinal tuberculosis patients can find pleural or pericardial effusion.Malignant mediastinal mass with.pleural or pericardial effusion was found only one case. Elastography showed diffuse increased hardness are all malignant mediastinal tumor. EUS-FNA in 88 cases achieved successful tissue diagnose is among all 92 attemptions. The sensitivity, specificity, positive predictive value, and negative predictive value were 93.0%,100%,100%,88.6%, respectively. EUS-FNA diagnosis and the final diagnosis Kappa values were detected, Kappa value is 0.903 (> 0.75).Conclusions:Echofeatures of mdiastinal mass likes heterogeneous echopattern, obscure boundary,Solid, rich in blood vessels,surrounding tissue infiltration and diffuse increased hardness are significant predictors of malignancy. In high tuberculosis prevalence regions the median of long axis cannot distinguish malignant masses and benign cases, A pleural effusion and pericardial effusion has reference value to the diagnosis of tuberculosis.EUS-FNA improves the accuracy of diagnosis.