Can endoscopic ultrasound distinguish between mediastinal benign lymph nodes and those involved by sarcoidosis, lymphoma, or metastasis?

BACKGROUND: Lymph nodes (LNs) echofeatures on endoscopic ultrasound (EUS) and concurrent fine needle aspiration (FNA) are alternatives to highly invasive approaches for etiologic diagnosis of mediastinal lymphadenopathy (MLAD). AIMS: To evaluate the efficacy of LNs echofeatures and FNA via EUS to distinguish benign LNs from LNs involved by sarcoidosis, lymphoma, and metastasis in non-lung cancer patients.
METHODS: A retrospective review of patients who underwent EUS-FNA for MLAD was performed. Echofeatures of LNs including echogenicity, margins, shape, and LN size were recorded. Final diagnosis was made based on surgical sampling or clinical diagnosis with long-term follow-up. Only patients diagnosed as benign MLAD, sarcoidosis, lymphoma, and metastasis included. Diagnostic value of echofeatures and FNA was evaluated.
RESULTS: Included were 162 patients with final diagnosis of benign (68), sarcoidosis (33), lymphoma (20), and metastasis (41). The median LN along axis in the benign group [20.5 mm (6-76)] was significantly shorter than in the metastasis [28 mm (9-82)] and sarcoidosis [27 mm (17-50)] groups (p < 0.05). The median LN short axis in the benign group [11 mm (2-50)] was significantly shorter than in the metastasis [17 mm (5-44)] and lymphoma [16 mm (7-47)] groups (p < 0.05). No other echofeatures showed a discriminant value among the groups. When performing FNA, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EUS-FNA were 73.7, 100, 100, 72.2, and 84.4 %, respectively.
CONCLUSION: Although benign MLAD tend to be smaller than other etiologies, echofeatures of LNs are not reliable etiologic diagnostic approach to MLAD. Therefore, FNA is suggested when feasible. However, due to relatively low sensitivity, LNs with benign FNA results should be subjected to further work-up if they are clinically suspicious.