111 Clinical Utility of EUS-Guided Needle-Based Confocal Endomicroscopy of Pancreatic Cystic Lesions for Surgical Decision Making

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INTRODUCTION: There is a need to assess the clinical impact of utilizing EUS-guided needle-based confocal endomicroscopy (nCLE) in the surgical management of PCLs. Hence, we sought to evaluate the concordance of diagnoses using the standard of care (SOC) clinical data with EUS-nCLE, and the impact on surgical resections of PCLs. METHODS: Subjects included consecutive patients enrolled in a prospective study (2015–2018) evaluating EUS-nCLE for the diagnosis of PCLs who underwent a clinically indicated EUS-FNA, along with EUS-nCLE. Data used to derive the SOC diagnosis included clinical history, cross-sectional imaging, EUS morphology, cyst fluid CEA, and cytology (based on hierarchical group assignment, Table 1). Decisions for patient management also involved multidisciplinary tumor board meetings. A final diagnosis of PCLs was defined for those with surgical histopathology or presence of established mutations in the cyst fluid (KRAS/GNAS: mucinous cyst, VHL: serous cystadenoma). The diagnostic concordance of EUS-nCLE alone with SOC was assessed. RESULTS: A total of 138 subjects with PCLs (mean cyst size 36.4 ± 15.7 mm) underwent SOC and EUS-nCLE. A final diagnosis was available in 93 subjects (surgical histopathology, n = 67, molecular markers in cyst fluid, n = 26). Diagnostic concordance was observed in 80 (86%) subjects, with a discordant nCLE diagnosis in the remaining 13 (14%) subjects. Among PCLs with discordant diagnoses (Table 2), EUS-nCLE was “clinically advantageous” in 11 subjects with successful downstaging of PCLs which were otherwise classified as mucinous by SOC, hence potentially preventing unwarranted surgery. In one subject, nCLE was “clinically advantageous” with successful upstaging of PCL (final diagnosis: IPMN), while SOC inaccurately classified the lesion as a non-mucinous PCL. EUS-nCLE was “clinically disadvantageous” in one subject (final diagnosis was mucinous cystic neoplasm) who were classified as a mucinous cyst by SOC, but nCLE did not reveal diagnostic image patterns. CONCLUSION: EUS-nCLE has a significant clinical impact by preventing at least one unwarranted pancreatic surgery for every ten subjects undergoing multimodality SOC evaluation. Hence EUS-nCLE should be considered for a comprehensive assessment of PCLs when FNA is being performed.