Diagnostic Performance of Pancreatic Cytology with the Papanicolaou Society of Cytopathology System: A Systematic Review, before Shifting into the Upcoming WHO International System

Abstract

The Papanicolaou Society of Cytopathology (PSC) reporting system classifies pancreatobiliary samples into six categories (I–VI), providing guidance for personalized management. As the World Health Organization (WHO) has been preparing an updated reporting system for pancreatobiliary cytopathology, this systematic review aimed to evaluate the risk of malignancy (ROM) of each PSC category, also the sensitivity and specificity of pancreatic FNA cytology using the current PSC system. Five databases were investigated with a predefined search algorithm. Inclusion and exclusion criteria were applied to select the eligible studies for subsequent data extraction. A study quality assessment was also performed. Eight studies were included in the qualitative analysis. The ROM of the PSC categories I, II, III, IV, V, VI were in the ranges of 8–50%, 0–40%, 28–100%, 0–31%, 82–100%, and 97–100%, respectively. Notably, the ROM IVB (“neoplastic—benign”) subcategory showed a 0% ROM. Four of the included studies reported separately the ROMs for the IVO subcategory (“neoplastic—other”; its overall ROM ranged from 0 to 34%) with low (LGA) and high-grade atypia (HGA). ROM for LGA ranged from 4.3 to 19%, whereas ROM for HGA from 64 to 95.2%. When the subcategory IVO with HGA was considered as cytologically positive, together with the categories V and VI, there was a higher sensitivity of pancreatic cytology, at minimal expense of the specificity. Evidence suggests the proposed WHO international system changes—shifting the IVB entities into the “benign/negative for malignancy” category and establishing two new categories, the “pancreatic neoplasm, low-risk/grade” and “pancreatic neoplasm, high-risk/grade”—could stratify pancreatic neoplasms more effectively than the current PSC system.

Risk of Malignancy Using the Diagnostic Categories Proposed by the World Health Organization International System for Reporting Pancreaticobiliary Cytopathology

“…In our study, the ROM under the PSC reporting system was as follows: I, nondiagnostic (ROM, 34%); II, negative (ROM, 1%); III, atypical (ROM, 50%); IV, neoplastic (overall ROM, 14,3%); IVB, neoplastic-benign (ROM, 0%); IVO, neoplastic-other (ROM, 16%); IVO with LGA (ROM, 5%); IVO with HGA (ROM, 100%); V, suspicious for malignancy (ROM, 88%); and IV, malignant (ROM, 100%). Our findings were similar to the literature [8]. Additionally, the ROM under the WHO reporting system was as follows: I, nondiagnostic (ROM, 35%); II, negative (ROM, 1%); III, atypical (ROM, 69%); IV, PaN-Low (ROM, 11%); V, PaN-High (ROM, 100%); VI, suspicious for malignancy (ROM, 91%); and VII, malignant (ROM, 100%), similar ROM to Hoda et al [23], except the “nondiagnostic” and “atypical” categories.…”

“…This difference in ROMs in the "atypical" category is due to the two SPN cases and one NET case in the cohort. In the literature, the "atypical" category has a ROM that ranges between 28% and 100%, in concordance with our results [8]. Specificity and PPV were higher when the "neoplastic: other with epithelial HGA/PaN-High," "suspicious," and "positive" was considered positive.…”

“…Diag- nostic performance of pancreatic cytology with the PSC reporting system has been published by many authors since 2014 [2,3,[15][16][17][18][19][20][21][22]. Recently, a systematic review has been published by Nikas et al [8], wherein ROM of all PSC system categories was reported as follows: I, nondiagnostic (ROM, 8-57%); II, negative (ROM, 0-40%); III, atypical (ROM, 28-100%); IV, neoplastic (overall ROM, 0-31%) IVB, neoplastic-benign (ROM, 0%); IVO, neoplastic-other (ROM, 0-34%); IVO with HGA (ROM, 64-100%); V, suspicious for malignancy (ROM, 80-100%); and IV, malignant (ROM, 97-100%) [8]. Hoda et al [23] have reported the absolute and relative ROM of 334 EUS-FNA samples under both the PSC and WHO international reporting systems.…”

“…Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) biopsy of the pancreas is a minimally invasive, safe, and accurate diagnostic test, with high sensitivity and specificity in evaluating pancreatic solid and cystic masses [ 1 , 3 , 4 , 5 , 6 , 7 ]. Aspirated material can be effectively triaged for cytomorphologic examination and biochemical and molecular tests for accurate diagnosis [ 8 ]. Pancreatic lesions' diagnosis and therapy is a multidisciplinary teamwork including radiologists, endoscopists, pathologists, surgeons, and medical and radiation oncologists.…”

“…The IVB category mostly comprises serous cystadenoma (SCA) and lymphangioma, whereas IVO is a heterogeneous category, including intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) of any grade, pancreatic neuroendocrine tumors (PanNETs), and solid pseudopapillary neoplasms (SPNs), with malignant potential [ 9 , 14 ]. The PSC reporting system provided a guide to the morphological criteria and risk stratification of each of the cytologic reporting categories incorporating radiologic, biochemical, and ancillary technique findings, and facilitated the communication between cytopathologists and clinicians [ 8 ].…”