RESUMEN
INTRODUCTION: Demonstration of diagnostic contribution of Papanicolaou Society of Cytopathology-standardized nomenclature for pancreaticobiliary cytology (PSC-PC) in endoscopic ultrasonography (EUS) fine-needle biopsy (FNA) biopsies is important for widespread use and further development. METHODS: 179 EUS-FNA biopsies (89: solid, 90: cystic) and PSC-PC categories were compared with surgical definite histopathology and definite clinical diagnosis. Overall risk of malignancy (oROM) was calculated for each PSC-PC category. Diagnostic accuracy was evaluated. RESULTS: The cytopathology of lesions was nondiagnostic in 27%. Ductal dilatation, lymphadenopathy, and solid characteristic (independently) were associated with diagnostic result, while lesion size was not. PSC-PC categories had 89% diagnostic consistency with surgical definite histopathology. Category mismatch was detected in 3 patients (11%), of which 2 had adenocarcinoma. oROM was 14.3% for nondiagnostic group, 46% for cat. III (atypia), and 12% for cat. IVB (neoplastic - other). In terms of malignancy, the PSC-PC system had 100% specificity; PPV, 92% sensitivity, and 81% NPV; and the diagnostic accuracy was 94%. CONCLUSION: Using PSC-PC in EUS-FNA biopsies, pancreatic malignancy can be diagnosed with high diagnostic accuracy. In mucinous cystic lesions, some malignancies may be missed. To predict the malignancy risk of cat. IVB, assessment of dysplasia seems important. Although PSC-PC is not the only parameter in terms of diagnosing malignancy, its contribution to the clinical decision is quite high.