Currently, the best way to evaluate pancreatic masses is through endoscopic-guided needle sampling of the mass to determine the diagnosis by looking at the acquired tissue under a microscope. This is done by inserting a small camera (endoscope) through the mouth of the patient then advanced to the stomach and using ultrasound guidance a sample of the pancreas can be acquired through the stomach. The sampling is usually done with a small needle called fine needle aspiration needle or FNA. FNA alone is sometimes limited due to inadequate acquisition of cells for proper diagnosis under the microscope, which can lead to need for repeat endoscopic procedures and delay in diagnosis and possibly treatment. Rapid on-site evaluation of cytopathology (ROSE) is where a cytopathologist is next to the physician doing the endoscopic procedures and evaluates each sampling performed immediately under the microscope and can give feedback to the endoscopist until enough cells has been acquired for a diagnosis. This method has been shown to increase the ability to diagnose pancreatic cancer but is expensive and requires significant amount of resources. New needles called core needles (fine needle biopsy, FNB) have recently been developed which not only acquires cells but also the entire tissue structure (histology) and has been shown to be also very accurate in the diagnosis of pancreatic cancer.

The purpose of this study is to compare endoscopy-guided biopsy of pancreatic masses with the new core needle (FNB), which can obtain more tissue for diagnosis vs. using a traditional needle (FNA) with the help of an immediate assessment of the obtained samples under the microscope to determine whether enough tissue has been obtained (ROSE). Both approaches have been shown to increase the accuracy of diagnosis in solid pancreatic masses but it is unclear which one is superior. This is a randomized trial meaning that the participants would either undergo biopsy with the new needle or with the traditional needle plus the addition of on-site assessment of the obtained samples. The advantage of the new needle is that it is easy to implement and likely much cheaper. If the investigators can show in our study that the new needles are as accurate as FNA with ROSE then FNB could be implemented across hospitals worldwide in an easier and less expensive fashion.

Inclusion Criteria:

• Age > 18 years
• Patients referred for EUS evaluation of a definite solid pancreatic mass noted on computed tomography(CT)/Magnetic resonance imaging(MRI)/EUS, in which malignancy is suspected with no previous histological diagnosis

Exclusion Criteria:

• Age < 18 years, pregnant patients.
• Uncorrectable coagulopathy Prothrombin time (PT) >50% of control, Partial Thromboplastin time (PTT) >50 sec, or International normalized ratio (INR) >1.5 and/or uncorrectable thrombocytopenia platelet count<50, 000109/L.