Needle based confocal laser endomicroscopy (nCLE) for the real-time diagnosis of mediastinal lymph nodes involved in sarcoidosis

Introduction: In patients with mediastinal lymphadenopathy a distinction between malignancy and granulomatous disorders is essential. Confocal laser endomicroscopy (CLE) enables real-time microscopic analysis during endososonography. CLE criteria of malignant lymph nodes have been proposed but are lacking for granulomas. Aim: To identify CLE criteria for real-time in-vivo recognition of granulomas on CLE imaging during endosonography (EUS). Methods: In patients with suspected sarcoidosis stage I-II, mediastinal lymph nodes were imaged with CLE through a 19 G needle in-vivo under EUS control, followed by fine needle aspiration. CLE videos were reviewed and compared to the final diagnoses based on cytology and clinical-radiological follow-up. Results: EUS-nCLE-FNA was performed in 17 patients (n=16 sarcoidosis, n=1 tuberculosis) and 29 lymph nodes were imaged. No adverse events occurred. On CLE imaging the granulomas appeared like oval, well-demarcated, lighter-toned lesions (Figure). Tuberculoid necrosis could be identified on CLE as a loss of contact signal. Conclusion: In suspected sarcoidosis patients, real-time in-vivo EUS-guided nCLE imaging is feasible and safe. Granulomas show a distinct CLE pattern different from malignant CLE-criteria previously described. nCLE provides real-time pathology feedback and can therefore potentially improve diagnostics of mediastinal and lung lesions.