Intraductal papillary mucinous neoplasm of the pancreas: Cytomorphology, imaging, molecular profile, and prognosis

Abstract

Background Intraductal papillary mucinous neoplasm (IPMN) constitutes up to 20% of all pancreatic resections, and has been increasing in recent years. Histomorphological findings of IPMN are well established; however, there are not many published papers regarding the cytological findings of IPMN on fine needle aspiration (FNA) specimens. We review the cytomorphological features, molecular profile, imaging findings, and prognosis of IPMN. Methods The English literature was thoroughly searched with key phrases containing IPMN. Observations IPMN is a rare entity, affecting men and women equally and is usually diagnosed at the age of 60‐70 years. The characteristic imaging features include a cystic lesion with associated dilatation of the main or branch pancreatic duct, and atrophy of surrounding pancreatic parenchyma. Cytomorphological features of IPMN include papillary fragments of mucinous epithelium in a background of abundant thick extracellular mucin, a hallmark feature. IPMNs should be evaluated for high‐grade dysplasia, which manifests with nuclear atypia, nuclear moulding, prominent nucleoli, nuclear irregularity, and cellular crowding. Molecular profiling of IPMN along with carcinoembryonic antigen and amylase levels is useful in predicting malignancy or high‐grade dysplasia arising in IPMN. Overall, the prognosis of IPMN is excellent except in those cases with high‐grade dysplasia and malignant transformation. Postoperative surveillance is required for resected IPMNs. Conclusion IPMN requires a multidisciplinary approach for management. Cytomorphological findings of IPMN on FNA, in conjunction with tumour markers in pancreatic fluid cytology and imaging findings, are of paramount importance in clinical decision‐making for IPMN.

Case report: Treatment of intraductal papillary mucinous neoplasms located in middle-segment pancreas with end-to-end anastomosis reconstruction after laparoscopic central pancreatectomy surgery through a pigtail-tube-stent placement of the pancreatic duct

“…Because the pancreatic cystic lesion was accompanied by a significantly dilated pancreatic duct (main pancreatic duct (MPD) diameter ≥ 10 mm), MD-IPMN should be considered for diagnosis in this case. Regardless of the diverse claims on the diameter of the MPD and the size of the cystic lesion, almost all guidelines such as AGA, ACR, and European guidelines suggest that surgery is recommended for MD-IPMN with high-risk stigmata ( 14 ). Due to the above reasons, we took surgical treatment measures for this case.…”

Background features in the cytology of pancreatic neoplasms

“…In addition, the mucinous background is easier to evaluate with conventional smears than with liquid-based cytology. 38…”

“…In general, pancreatic neoplasms have thick, colloidal mucin, whereas gastroduodenal mucin is more watery and colloid-like. 38 However, it is difficult to distinguish gastroduodenal mucin from pancreatic neoplasm mucin; therefore, it is important to carefully evaluate cellular morphology and other factors for diagnosis. In addition, the mucinous background is easier to evaluate with conventional smears than with liquid-based cytology.…”

“…Therefore, care should be taken not to misinterpret the contamination of gastric duodenal mucus as the mucinous background of pancreatic neoplasms when assessing the findings of EUS‐FNA cytology. In general, pancreatic neoplasms have thick, colloidal mucin, whereas gastroduodenal mucin is more watery and colloid‐like 38 . However, it is difficult to distinguish gastroduodenal mucin from pancreatic neoplasm mucin; therefore, it is important to carefully evaluate cellular morphology and other factors for diagnosis.…”

The basics of commonly used molecular techniques for diagnosis, and application of molecular testing in cytology

“…19 Molecular testing can also be used in cytology samples obtained by endoscopic retrograde cholangiopancreatography (ERCP) to help make more definitive diagnoses of lesions in the pancreaticobiliary tract. 5,20,21 As molecular testing has become essential for patient care and is often requested to be performed using cytology samples, pathologists must understand the basics of molecular diagnostic methodology, indications for molecular testing, and how to best utilize various cytological samples for molecular testing. As with all laboratory tests, good starting material is crucial for accurate test results.…”