Objective Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a minimally invasive technique with a high diagnostic yield used in the investigation of mediastinal diseases including sarcoidosis. Although previous reports have discussed the echoic features of metastatic mediastinal lymph nodes in lung cancer, few have addressed those features of mediastinal lymph nodes with sarcoidosis. We therefore investigated whether the echoic features of lymph nodes with sarcoidosis are distinct when compared to those of metastatic lymph nodes in lung cancer. Methods This retrospective analysis was held in one university hospital between April 2007 and June 2011. EBUS-guided biopsies were performed on 219 patients, and thus resulting in sarcoidosis diagnoses in 53 patients. We quantitatively analyzed the echoic morphologic features of 42 lymph nodes from 34 sarcoidosis patients and 59 lymph nodes from 44 patients with lung cancer using digital image analyzing software. Results In patients with sarcoidosis, 64.3% of the lymph nodes had a round shape, 71.4% had a distinct margin, and 88.1% exhibited homogeneous echogenicity. A germinal center structure was observed in 71.4% of the cases. In the context of shape and margin, no significant difference could be observed between sarcoidosis and lung cancer metastasis. However, homogeneous low echogenicity and the presence of a germinal center structure were observed in sarcoidosis more frequently than in lung cancer. Conclusion Homogeneous low echogenicity and the presence of a germinal central structure may be distinctive echoic features of lymph nodes with sarcoidosis. Analyzing the echogenicity of the mediastinal lymph nodes may help to distinguish sarcoidosis from lung cancer.
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