Macroscopic on-site evaluation after EUS-guided fine needle biopsy may replace rapid on-site evaluation

Background and Objectives: Rapid on-site cytologic evaluation (ROSE) increases the diagnostic yield of EUS-FNA. However, ROSE requires the presence of a cytopathologist and additional cost and time for slide staining and interpretation. Macroscopic on-site examination (MOSE) was recently introduced as an alternative to ROSE and showed high accuracy for the use in pathologic diagnosis. We evaluated the efficacy of MOSE in terms of tissue acquisition and diagnostic accuracy for abdominal lesions. Methods: We analyzed consecutive patients included who underwent EUS-guided fine needle biopsy (FNB) between January 2019 and November 2019. All procedures were done by dry suction using a 22G needle. Obtained specimens were expelled onto filter papers and evaluated by MOSE. Needle pass was done until the acquisition of satisfactory whitish macroscopic visible core or bloody tissue granules. The primary outcomes were successful tissue acquisition and accuracy for pathologic diagnosis. Results: In 75 patients (male, 52%; median age: 62 years), the pancreas was the most commonly targeted organ (81.4%) and the median target diameter was 25 mm. The median number of needle passes was 2.0 (range, 2-5). Successful targeting of the lesion was achieved in 75 patients (100%) and overall accuracy was 97.3%. There were no procedure-related adverse events. Conclusions: MOSE was effective for complementing EUS-FNB by ensuring the adequate acquisition of biopsy specimens with a minimal number of needle passes while providing a critically high diagnostic accuracy. MOSE seems to be a viable alternative to ROSE in select clinical situations.