Use of Endoscopic Scraper and Cell Block Technique as a Replacement for Conventional Brush for Diagnosing Malignant Biliary Strictures

SIMPLE SUMMARY: Brush cytology remains the primary method used worldwide for diagnosing malignant biliary strictures, despite its low sensitivity. Although the endoscopic scraper, the simplicity of which is comparable to that of a conventional brush, has been used mainly in Japan, it has yet to gain popularity on a global scale. The purpose of this study was to evaluate the diagnostic performance of the endoscopic scraper by comparing diagnostic yields and the number of collected cells using quantitative digital image analysis. Our study revealed that the endoscopic scraper and cell block method achieved higher sensitivity than the brush with the cell block method, and showed that the number of cells on the cell block sections obtained by the endoscopic scraper were significantly higher than those obtained using the brush. Given its ease of use and high sample acquisition capability, the endoscopic scraper could replace brush cytology for diagnosing malignant biliary strictures. ABSTRACT: Histological evidence is essential for diagnosing malignant biliary strictures. However, conventional brush cytology remains the primary method used worldwide, despite its low diagnostic sensitivity and accuracy, as it is technically easy, rapid, and cost-effective. The aim of this study was to evaluate the diagnostic performance of a recently introduced endoscopic scraper, the simplicity of which is comparable to that of a conventional brush, by comparing diagnostic yields and the number of collected cells. The sensitivity of the endoscopic scraper when using the cell block technique was significantly higher than when using brush cytology or a brush with the cell block technique (53.6% vs. 30.9%, p < 0.001; 53.6% vs. 31.6%, p = 0.024, respectively). Quantitative digital image analysis of cell block sections revealed that the median number of cells obtained with the endoscopic scraper was significantly higher than when using the brush (1917 vs. 1014 cells, p = 0.042). Furthermore, seven cases (8.3%; 7/84) were diagnosed by immunohistochemical analysis of the cell block section obtained from the endoscopic scraper. Given its simplicity and greater capacity for sample acquisition, use of the endoscopic scraper in conjunction with the cell block technique could replace brush cytology for the histological diagnosis of malignant biliary strictures.