Irregular echogenic foci representing coagulation necrosis: A useful but perhaps under-recognized EUS echo feature of malignant lymph node invasion

Background and Aims: Coagulation necrosis has been described in malignant lymph nodes. Our aim was to determine if coagulation necrosis in mediastinal lymph nodes imaged by EUS could be used as a useful echo feature for predicting malignant invasion. Methods and Design: Patients with known or suspected lung cancer who had undergone mediastinal lymph node staging by EUS. Setting: Tertiary Care university hospital. Participants and Intervention: An expert endosonographer blinded to the final diagnosis, reviewed the archived digital EUS images of lymph nodes prior to being sampled by FNA. LNs positive for malignancy by FNA were included. The benign group included lymph node images with either negative EUS-FNA or lymph nodes imaged by EUS but not subjected to EUS-FNA, with surgical correlation of their benign nature. Results: 24 patients were included. 8 patients were found to have coagulation necrosis. 7/8 patients had positive result for malignancy by EUS-FNA. One patient determined to have coagulation necrosis had a non-malignant diagnosis indicating a false positive result. 16 patients had no coagulation necrosis. In 6 patients with no coagulation necrosis, the final diagnosis was malignant and in the remaining 10 cases, the final diagnosis was benign. For coagulation necrosis as an echo feature for malignant invasion, sensitivity was 54%, specificity was 91%, positive predictive value was 88%, negative predictive value was 63% and accuracy was 71%. Conclusion: Coagulation necrosis is a useful echo feature for mediastinal lymph node staging by EUS.