EUS-GUIDED FNA OF SOLID PANCREATIC MASSES: DO WE NEED THE FOURTH PASS? A PROSPECTIVE STUDY

Aims Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is important for the differential diagnosis of solid pancreatic lesions. However, the sample adequacy is related to the number of needle passes. The European guidelines recommend performance of three to four needle passes with the standard EUS FNA needle.

Our aim is to evaluate the optimum number of passes with standard EUS-FNA needles in solid pancreatic lesions.

Methods There were included prospectively patients with solid pancreatic masses on CT scan, without cystic component over 20%, biliary metallic stents or coagulation problems. The 22G Olympus standard needle were used (maximum four passes), each sample was paraffin embedded and analysed separately. The final diagnosis was established by EUS-FNA, repeated EUS-FNA, surgery or follow-up.

Results There were included 61 patients with masses localized in the pancreatic head(62%), with the mean size=3.3±0.4 mm. The final diagnosis was adenocarcinoma (n=39, 62%), neuroendocrine tumor (n=10, 19%), others (n=4,6 %). Immunohistochemistry by EUS-FNA samples was possible in 17 (26%) of cases. The diagnosis was established by the first pass in 52% of cases (n=32), by the second pass in 14% of cases (n=9), by the third pass in 16% of cases (n=10) and by the fourth pass in 3% of cases (n=2), there were 8 false negative cases. The diagnosis accuracy for all four passes compared to the first three passes was 86% vs 83%, p= 0.832, between the first three passes compared to the first two passes was 83% vs 76%, p=0.567. The contribution of the fourth pass was not different for adenocarcinoma or NET (2% vs. 10%, p=0.28).

Conclusions Three passes with the standard EUS-FNA was optimal for a specific diagnosis of solid pancreatic masses, no matter the histologic type of the lesion.