EUS-GUIDED TISSUE ACQUISITION IN CHRONIC PANCREATITIS: DIFFERENTIAL DIAGNOSIS BETWEEN PANCREATIC CANCER AND PSEUDOTUMORAL MASSES USING EUS-FINE NEEDLE ASPIRATION OR CORE BIOPSY

Aims Endoscopic Ultrasound (EUS)-guided fine needle aspiration (FNA) sensitivity for malignancy in parenchymal masses of patients with concurrent chronic pancreatitis (CP) has been reported to be unsatisfactory. The aim of the present study was to directly compare the diagnostic accuracy of EUS-FNA and EUS-fine needle biopsy (FNB) in differentianing between inflammatory masses and malignancies in the setting of CP.

Methods We performed a retrospective analysis of prospective, multicentric databases of all subjects with pancreatic masses and clinical-radiological-endosonographic features of CP who underwent EUS-FNA or FNB. The diagnosis of CP was made in accordance with current International Guidelines. Endosonographic features of CP were described in accordance with Rosemont criteria; all patients with “indeterminate” or “normal” EUS imaging were excluded. Sensitivity, specificity, PPV, NPV and overall accuracy of EUS-FNB were calculated. A binary logistic regression was used to examine the possible predictors for a correct diagnosis.

Results Among 1124 with CP, 210 patients (60% males, mean age 62.7 years) with CP and

pancreatic masses met the inclusion criteria and were enrolled. In the FNA group (110 patients), a correct diagnosis was obtained in all but 18 cases (diagnostic accuracy 83.6%, sensitivity 69.5%, specificity 100%, PPV 100%, NPV 73.9%); by contrast, among 100 patients undergoing FNB, a correct diagnosis was obtained in all but 7 cases (diagnostic accuracy 93%, sensitivity 86.8%, specificity 100%, PPV 100%, NPV 87%) (p=0.03, 0.03, 1, 1 and 0.07, respectively). At binary logistic regression, focal pancreatitis (OR 4.9; p< 0.001), higher Ca19-9 (OR 2.3; p=0.02) and FNB (OR 2.5; p< 0.01) were the only independent factors associated with a correct diagnosis.

Conclusions EUS-FNB is effective in the differential diagnosis between pseudotumoral masses and solid neoplasms in CP, showing higher diagnostic accuracy and sensitivity than EUS-FNA. EUS-FNB should be considered the preferred diagnostic technique for diagnosing cancer in the setting of CP.