Endoscopic ultrasonography (EUS) with tissue acquisition (TA) is nowadays a well-established technique for the sampling of solid lesions pancreatic and non-pancreatic lesions. Major complications after EUS-TA of solid masses are rare. Several studies have been published in the last recent years aimed to identify factors related to a non-diagnostic or false-negative EUS-FNA, and to improve its diagnostic yield using different needle gauge and different tissue acquisition technique as fanning technique, slow-pull stylet extraction or suction technique.

To overcome this problem, new EUS-TA needles entered in clinical practice to obtain histological specimens increasing the accuracy of the EUS-TA. Preliminary result with these new needles, called EUS-fine needle biopsy (FNB) are promising with an accuracy rate more than 90%.

Recently, Leungh et al. conducted an observational study to evaluate the role of macroscopic on-site evaluation (MOSE) on the diagnostic accuracy of 22G Franseen-tip needle. The study demonstrated that MOSE using the 22G Franseen tip needle could limit needle passes by accurately estimating histologic core fragments. However, the study limitations such as the small sample size and the lack of control group, hampered the value of the conclusions.

So, nowadays, no definitive data regarding how many needle passes need to be performed with FNB needles, neither regarding the use of MOSE to evaluate the specimens obtained with FNB needle. The MOSE technique of the acquired tissue was proposed for the first time by Iwashita et al, using a 19G needle and is nowadays a well-established technique with high accuracy in the final diagnosis.

The aim of our study is to evaluate if during EUS-FNB of pancreatic masses only one needle pass with MOSE evaluation can be satisfactory to obtain a correct diagnosis.

Inclusion Criteria:

• Age greater than 18, both genders.
• Both in-patient and out-patients.
• Presence of a solid lesion. In the presence of a cystic component, the solid part of the lesion should be more 75% of the total.
• FNB performed by a 22G needle Acquire® (Boston Scientific).
• Tissue acquisition with fanning technique.
• Able to obtained informed consent.

Exclusion Criteria:

• Patients underwent EUS-FNA with or without ROSE
• Patients underwent EUS-FNB plus ROSE.
• Previous biopsy of the lesion with diagnosis of malignancy
• Presence of an uncorrectable coagulopathy as defined by abnormal prothrombin time (PT) or partial thromboplastin time (PTT) that does not normalize after administration of fresh frozen plasma.
• Pregnancy or breast-feeding.
• Patients unable to understand and/or read the consent form.

79 patients with solid pancreatic masses underwent EUS-FNB will be included.