Coagulation necrosis in malignant mediastinal nodes on endoscopic ultrasound: a new endosonographic sign

Abstract

Endoscopic ultrasound (EUS) can be used to assess mediastinal lymph nodes, and EUS-guided transoesophageal fine needle aspiration (EUS-FNA) can provide a tissue diagnosis. Previous studies suggest that a uniformly hypoechoic echotexture is a feature of malignant nodes, and echogenic structures within nodes are due to the normal hilum. Ill-defined, non-shadowing echogenic areas within malignant lymph nodes have been termed coagulation necrosis (CN) on neck ultrasound. The purpose of this study is to determine whether CN can be detected on EUS and be used as a predictive sign for malignancy in mediastinal lymph nodes. A total of 36 individuals who underwent EUS-FNA of mediastinal lymph nodes were initially included. A radiologist experienced in neck ultrasound, and blinded to the final diagnosis, reviewed hard-copy films for CN. Comparison was made with the EUS-FNA result and the final diagnosis. Four patients were excluded because their films were deemed inadequate for retrospective diagnosis. The remaining 32 patients were all included, and 11 showed CN. Of the 11 cases, 10 had malignant cytology on EUS-FNA; and in the remaining case follow-up indicated a false-negative EUS-FNA. Of the 21 subjects with no CN, the final diagnosis was malignant in 12 and non-malignant in 9 cases. No participant with a final benign diagnosis had CN. Echogenic structures within mediastinal lymph nodes on EUS are not necessarily due to the normal hilum. Careful analysis of the intranodal echo pattern may reveal CN. CN can be used as a predictive sign of malignancy and EUS-FNA should be targeted towards these nodes.