Pancreatic juice cytology as sensitive test for detecting pancreatic malignancy in intraductal papillary mucinous neoplasm of the pancreas without mural nodule.

OBJECTIVE: Recent studies reported that mural nodule (MN) was the most associated with malignant intraductal papillary mucinous neoplasms (IPMNs). However, IPMNs without MN cannot be diagnosed as malignant if only MN is determined to be indicator of malignancy. This study aimed to investigate role of pancreatic juice cytology for IPMNs without MN.

METHODS: Medical records of 50 patients with histologically proven malignant IPMNs were reviewed. Exclusively for non-invasive cancer, extent of high-grade dysplasia along the main pancreatic duct (MPD) was determined microscopically.

RESULTS: Thirty-six percent IPMNs had no MN. Cyst and main MPD diameter were significantly smaller in IPMN without MN compared to those in IPMN with MN (23 ± 14.1 vs 35 ± 13.2 mm, p = 0.010; 6.6 ± 4.3 vs 10.9 ± 6.1 mm, p = 0.006). Sensitivity of pancreatic juice cytology was higher in IPMN without MN compared to that in IPMN with MN (94% vs 53%, p = 0.004) although it could be affected by selection bias of study patients. Absence of MN was determined to be an independent factor associated with true positive cytology (OR = 24.3, p = 0.005). Extent of high-grade dysplasia was significantly longer in IPMN with true positive cytology compared to that in IPMN with false negative cytology (46.8 ± 20.5 vs 26.4 ± 11.0 mm, p = 0.005), and tended to be longer in IPMN without MN compared to that in IPMN with MN (47.0 ± 19.0 vs 36.0 ± 20.1 mm, p = 0.16).

CONCLUSIONS: Sensitivity of pancreatic juice cytology was excellent in IPMN without MN. Pancreatic juice cytology may be a sensitive test for detection of pancreatic malignancy in IPMN without MN compared to high-risk imaging features.