Endoscopic ultrasound‐guided needle‐based confocal laser endomicroscopy in gastrointestinal subepithelial lesions: Feasibility study

Background and Aim Needle‐based confocal laser endomicroscopy (nCLE) allows for real‐time optical biopsies during endoscopic ultrasound‐guided fine‐needle aspiration (EUS‐FNA). Little is known about nCLE imaging of gastrointestinal subepithelial lesions (GI‐SEL); therefore, we determined its feasibility. Methods We carried out EUS, nCLE, and finally FNA in 25 patients with GI‐SEL between November 2015 and December 2018. We retrospectively compared nCLE findings with pathological findings of EUS‐FNA or surgical specimens. For concordance analysis, two endoscopists independently validated representative nCLE images 5 months or more after examinations. Results Adequate sample acquisition rate of EUS‐FNA was 67% per needle pass and 96% per patient. EUS‐FNA was diagnostic in 80% (20/25), suspicious in 4% (1/25), and nondiagnostic in 16% (4/25). nCLE image acquisition rate was 100% and its concordance rate with final pathology was 88% (22/25), which was not significantly different from diagnostic and suspicious EUS‐FNA. nCLE could differentiate GI stromal tumors (GISTs) from leiomyoma, in that GISTs were characterized by contrast‐enhanced densely populated spindle cell tumors with unenhanced rod‐shaped nuclei in 93% of 14 patients, whereas leiomyomas were characterized by narrower spindle cell tumors with fewer and smaller unenhanced nuclei in 100% of three patients. In rectal metastasis from lung adenocarcinoma, some pleomorphic dark nests were observed. At concordance analysis between the two endoscopists’ validation results, κ value was 0.560 (P