Despite the utility of rapid on-site cytological examination (ROSE) in Endoscopic Ultrasound-Guided Tissue Acquisition (EUS-TA), it is not uniformly performed in all centers because of limited availability. Macroscopic on-site examination (MOSE) is an alternative method that improves diagnostic ability depending on the visible whitish core length. Cell Block method is suitable for evaluating histological architecture, immunostaining, and molecular studies. We evaluated diagnostic performance of MOSE with core biopsy and Cell Block method using core biopsy needles

EUS guided Fine Needle Biopsy (FNB) was performed using cell block method and MOSE with core biopsy. The primary and secondary outcome measures were diagnostic accuracy, diagnostic yield, sensitivity, specificity, positive and negative predictive values, and the number of passes, respectively. The optimum length for macroscopic visible core (MVC) by MOSE to achieve accurate diagnosis was evaluated.

Ninety-six patients (48 cell block and 48 MOSE) were enrolled. Mean lesion size was larger in MOSE group (33.23±24.35mm vs 27.88±12.32 mm P = 0.692). Diagnostic accuracy (93.75%), diagnostic adequacy (79.17%), sensitivity (92.68% vs 92.86%), specificity (100%), positive predictive value (100%), negative predictive value (70% vs 66.67% P= 0.612) of the two methods were similar. Mean number of needle passes in MOSE was significantly lower (1.77 vs 2.44, p value <0.001). Mean core length in MOSE group was 12.31 mm ± 7.67 mm. Area under receiver operating characteristic curve analysis showed that core length of ³5mm gives a high sensitivity (93%) for specific diagnosis. Immunohistochemistry results were also obtained in both the groups when required (12.5% in MOSE group vs 18.75% in Cell Block group, P= 0.399).

Cell block and MOSE method in EUS FNB both yields comparable results but number of passes required are less in MOSE group. Obtaining longer core length increase sensitivity for specific diagnosis in MOSE group. If adequate core can’t be obtained, cell block method also gives comparable results. Besides, it also useful for preserving architectural composition and for immunohistochemistry studies.