Prospective analysis of atypical epithelial cells as a high-risk cytologic feature for malignancy in pancreatic cysts

Pancreatic cysts are aspirated to assess whether a cyst is mucinous on one hand and malignant on the other. The authors' retrospective data have indicated that high-grade atypical epithelial cells (AECs) identified on cytology are a high-risk feature and a better threshold than "positive" for detecting malignancy. The objective of the current study was to assess the accuracy of AECs in predicting malignancy in pancreatic cysts.

Cysts aspirated by endoscopic ultrasound (EUS)-guided fine-needle aspiration (EUS-FNAs) obtained between January 2006 and June 2011 were evaluated. Cytologic, histologic, imaging, and cyst fluid analysis data were recorded. AECs were defined as cells that had an increased nuclear-to-cytoplasmic ratio and nuclear hyperchromasia with or without membrane abnormalities and with or without cytoplasmic vacuoles, but of insufficient quality and quantity for a "positive" interpretation. Malignancy included mucinous cysts with high-grade dysplasia and invasive carcinoma. Performance characteristics of cytology with AECs or worse (high-grade atypia [HGA]) for predicting malignancy were assessed.

There were 70 FNAs that had histologic confirmation from 404 EUS-FNAs in 352 patients. Excluding 4 nondiagnostic FNAs, the study cohort consisted of 66 FNAs for analysis. There were 24 malignant cysts with 20 true-positive, 4 false-negative, 36 true-negative, and 6 false-positive results. For the detection of malignancy, HGA had 83% sensitivity, 86% specificity, a positive predictive value of 77%, a negative predictive value of 90%, and 85% overall accuracy. The lower threshold for malignancy with AECs resulted in a 12% increase in the detection of malignancy.

A finding of AECs on cytology is a high-risk feature for malignancy and is an accurate triage threshold for resection. Cancer (Cancer Cytopathol) 2013;121:29-36 © 2012 American Cancer Society.