 The sample size has been calculated in order to demonstrate the non-inferiority of EUS-FNB without ROSE compared to EUS-FNB with ROSE in terms of diagnostic accuracy, having established a clinically acceptable margin of non-inferiority of 5. The reported diagnostic accuracy of EUS-FNA with ROSE is 92. With a type I error α of 5 and a power 1 - β of 80, the total required sample size amounts to 730 patients one-sided hypothesis testing of categorical data, comparing two binomial proportions of independent samples. Calculations executed with PASS, version 14.0.3. Considering, than, a 9.5 of patients to add in order to counteract the estimated rate of drop-out and lost to follow-up, 800 patients will be needed on the whole that is 400 per group. 