Tumor Location in the Head/Uncinate Process and Presence of Fibrosis Impair the Adequacy of Endoscopic Ultrasound-Guided Tissue Acquisition of Solid Pancreatic Tumors

SIMPLE SUMMARY: Endoscopic ultrasound-guided tissue acquisition is the most accurate method to diagnose pancreatic tumors; nevertheless, this technique does not always bring adequate diagnostic accuracy. This study aimed to identify which factors can impair its adequacy. Pancreatic cytological and histological aspirates were retrospectively assessed according to two scores for grading the adequacy and the fibrosis of the specimens. The performance of the biopsies was lower when the tumor was located in the head/uncinate process of the pancreas, probably due to the higher fibrosis that we found in these sites. The specimens were less adequate also when <3 needle passes were performed and when the cell block was not done. We demonstrated the benefit to assess the presence of fibrosis in the specimens because it increased the risk of false negative results. ABSTRACT: Endoscopic ultrasound-guided tissue acquisition (EUS-TA) of solid pancreatic tumors shows optimal specificity despite fair sensitivity, with an overall suboptimal diagnostic yield. We aim to quantify the adequacy and accuracy of EUS-TA and assess predictive factors for success, focusing on the presence and degree of specimen fibrosis. All consecutive EUS-TA procedures were retrieved, and the specimens were graded for sample adequacy and fibrosis. The results were evaluated according to patients’ and tumor characteristics and the EUS-TA technique. In total, 407 patients (59% male, 70 [63–77] year old) were included; sample adequacy and diagnostic accuracy were 90.2% and 94.7%, respectively. Fibrosis was significantly more represented in tumors located in the head/uncinate process (p = 0.001). Tumor location in the head/uncinate (OR 0.37 [0.14–0.99]), number of needle passes ≥ 3 (OR 4.53 [2.22–9.28]), and the use of cell block (OR 8.82 [3.23–23.8]) were independently related to adequacy. Severe fibrosis was independently related to false negative results (OR 8.37 [2.33–30.0]). Pancreatic tumors located in the head/uncinate process showed higher fibrosis, resulting in EUS-TA with lower sample adequacy and diagnostic accuracy. We maintain that three or more needle passes and cell block should be done to increase the diagnostic yield.