The impact of macroscopic on-site evaluation using filter paper in EUS-guided fine-needle biopsy

BACKGROUND AND OBJECTIVES: EUS-guided tissue acquisition with rapid on-site cytologic evaluation (ROSE) has been used to increase the diagnostic yield. However, ROSE is not available in many centers. To date, only a few studies have assessed the adequacy of histologic cores in macroscopic on-site evaluation (MOSE) during EUS-guided fine-needle biopsy (EUS-FNB). Blood contamination of histologic core specimens lowers the sample quality and the diagnostic yield. Therefore, we evaluated the efficacy of MOSE using filter paper to increase the adequacy of histologic core specimens while minimizing blood contamination. MATERIALS AND METHODS: Seventy-nine consecutive patients with an intraabdominal mass underwent EUS-FNB between March 2017 and October 2018. Histologic specimens obtained using EUS-FNB were expelled onto filter paper, and the histologic procurement rate on MOSE was evaluated. RESULTS: EUS-FNB using a 20-gauge Procore needle or a 22-gauge Acquire needle was successful in all patients. The mean number of needle passes was 2.8 ss0.8. Visible histologic cores were observed in 94.9% (75/79) of the patients. Blood-contaminated specimens with scanty histologic cores were obtained in 5.1% (4/79) of the patients. On microscopic examination, 92.4% (73/79) of the histologic samples were graded as optimal. The diagnostic accuracy, sensitivity, and specificity were 94.5%, 94.3%, and 100%, respectively. Mild postprocedural adverse events occurred in 2 patients (2.5%: n = 1, transient fever; n = 1, acute pancreatitis). CONCLUSIONS: MOSE using filter paper provided adequate histologic samples while minimizing blood contamination. MOSE can also increase the diagnostic accuracy when ROSE is not available.