Significance of normal appearance on endoscopic ultrasonography in the diagnosis of early chronic pancreatitis

Background and Objectives: The Rosemont classification (RC) was developed as a consensus-based standard for the diagnosis of chronic pancreatitis (CP) by endoscopic ultrasonography (EUS), however, it is more complicated than the conventional scoring system. We have noticed that in the early stages of CP, it is not unusual to observe pancreas with abnormal appearance coexisting with the areas of normal parenchyma. The aim of this study was to investigate the validity of a "normal" pancreas appearance and to evaluate the usefulness of modified diagnostic criteria in comparison to the traditional EUS criteria and the RC. Patients and Methods: One hundred and seventy-seven patients who had undergone both EUS and endoscopic retrograde pancreatography (ERP) within 2 months were enrolled in the study, and patients with pancreatic cancer were excluded from the study. ERP findings were used as the gold standard for the diagnosis of CP. The EUS images obtained were classified according to both the RC and our new modified criteria. The latter includes an additional criterion to the modified traditional criteria: fine-reticular pattern (F-RP) was defined as a normal pancreatic parenchyma. We compared the accuracy between the new modified EUS criteria and the RC. Results: (1) Normal or equivocal findings on ERP were obtained for 132 patients; 113 patients had F-RP on EUS. In contrast, F-RP was found in only 6 out of 45 CP cases on ERP (P < 0.0001). (2) We investigated the diagnostic capability of our new criteria for endoscopic retrograde cholangiopancreatography normal/equivocal pancreas compared to the traditional criteria. In cases where fewer than two points were defined as normal, the incidence of normal pancreas was significantly higher based on the new criteria than on the traditional criteria (P = 0.002). (3) No significant differences were found between the new criteria and the RC across all ERP grades. Conclusion: Our new proposed "normal-added EUS criteria" for diagnosing CP was equivalent to the RC.