Update on risk stratification in the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology categories: 3‐year, prospective, single‐institution experience

BACKGROUND: Risk stratification is a critical element for the successful implementation of cytopathology reporting systems. To the authors' knowledge, there are limited prior studies regarding risk stratification for The Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology (PSCPC). In the current study, the authors reported on a single-institution experience on 3-year prospective PSCPC regarding risk of malignancy (ROM) and the overall risk of malignancy (OROM). METHODS: A computerized search was performed from August 2014 to December 2017 for all pancreatic fine-needle aspiration (FNA) samples. Pathology from surgical resections and biopsies and relevant radiologic and clinical follow-up data were collected. The ROM and the OROM were calculated. The OROM was based on the total number of FNA samples in each category. RESULTS: A total of 1017 pancreatic FNA cases were identified, with surgical and/or clinical follow-up data available for 548 cases. The cytopathologic diagnoses included 242 nondiagnostic (category I), 162 benign (category II), 142 atypical (category III), 20 neoplastic-benign (category IV: benign), 133 neoplastic-other (category IV: other), 28 suspicious (category V), and 290 malignant (category VI) cases. A total of 364 malignancies were documented in 11 cases, 4 cases, 36 cases, 0 cases, 36 cases, 21 cases, and 255 cases, respectively, from categories I, II, III, IV: benign, IV:other, V, and VI. The ROM was 25%, 17.4%, 41.8%, 0%, 34.3% (95.2%), 95.5%, and 99.6%, respectively, and the OROM was 4.5%, 2.5%, 25.3%, 0%, 27.1% (83.3%), 75%, and 87.9%, respectively, for categories I, II, III, IV: benign, IV: other (with high-grade dysplasia), V, and VI. CONCLUSIONS: The true ROM for PSCPC is likely between the ROM and OROM for the benign and indeterminate categories. In the neoplastic-other category (category IV: other), identifying high-grade dysplasia is important for its association with malignancy and a higher ROM.