Indication for resection and possibility of observation for intraductal papillary mucinous neoplasm with high-risk stigmata

Systematic review of challenging issues in pathology of intraductal papillary mucinous neoplasms

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are a cystic precursor to pancreatic cancer. IPMNs deemed clinically to be at high-risk for malignant progression are frequently treated with surgical resection, and pathological examination of the pancreatectomy specimen is a key component of the clinical care of IPMN patients.

METHODS

Systematic literature reviews were conducted around eight topics of clinical relevance in the examination of pathological specimens in patients undergoing resection of IPMN.

RESULTS

This review provides updated perspectives on morphological subtyping of IPMNs, classification of intraductal oncocytic papillary neoplasms, nomenclature for high-grade dysplasia, assessment of T stage, distinction of carcinoma associated or concomitant with IPMN, role of molecular assessment of IPMN tissue, role of intraoperative assessment by frozen section, and preoperative evaluation of cyst fluid cytology.

CONCLUSIONS

This analysis provides the foundation for data-driven approaches to several challenging issues in the pathology of IPMNs.

Adenosquamous carcinoma coexisting with intraductal papillary mucinous neoplasm of the pancreas: a case report

BACKGROUND

Adenosquamous carcinoma of the pancreas is a rare variant, with a worse prognosis than pancreatic ductal adenocarcinoma; moreover, it has characteristic clinical and histopathological features. Studies have mentioned the differentiation of intraductal papillary mucinous neoplasms into mucinous/tubular adenocarcinomas; however, their transdifferentiation into adenosquamous carcinoma remains unclear.

CASE PRESENTATION

An 80-year-old Japanese woman was referred to our hospital for further examination of multiple pancreatic cysts. Enhanced computed tomography after close follow-up for 6 years revealed a new nodule with poor enhancement on the pancreatic body. Distal pancreatectomy and splenectomy were performed. Histopathological examination revealed an adenosquamous carcinoma with coexisting intraductal papillary mucinous neoplasms; moreover, the intraductal papillary mucinous neoplasms lacked continuity with the adenosquamous carcinoma. Immunohistochemical analysis revealed squamous cell carcinoma and differentiation from adenocarcinoma to squamous cell carcinoma. Gene mutation analysis revealed KRAS^G12D and KRAS^G12R mutations in adenosquamous carcinoma components and intraductal papillary mucinous neoplasm lesions, respectively, with none showing the mutation of GNAS codon 201. The final histopathological diagnosis was adenosquamous carcinoma with coexisting intraductal papillary mucinous neoplasms of the pancreas.

CONCLUSIONS

This is the rare case of adenosquamous carcinoma with coexisting intraductal papillary mucinous neoplasms of the pancreas. To investigate the underlying transdifferentiation pathway of intraductal papillary mucinous neoplasms into this rare subtype of pancreatic cancer, we explored gene mutation differences as a clinicopathological parameter.

Surveillance after resection of non-invasive intraductal papillary mucinous neoplasms (IPMN). A systematic review

BACKGROUND

The ideal surveillance strategy after partial pancreatectomy for non-invasive IPMN remains undefined and existing guidelines provide conflicting recommendations. The present study was developed in anticipation of the joint meeting of the International Association of Pancreatology (IAP) and the Japan Pancreas Society (JPS) held in Kyoto in July 2022.

METHODS

An international team of experts developed the four clinical questions (CQ) to operationalize issues pertaining to surveillance of patients in this context. A systematic review was designed following the PRISMA guidelines and registered in PROSPERO. The search strategy was executed in PubMed/Medline (Ovid), Embase, the Cochrane Library and Web of Science databases. Four investigators individually extracted data from the selected studies and drafted recommendations for each CQ. These were subsequently discussed and agreed upon that the IAP/JPS meeting.

RESULTS

From a total of 1098 studies identified through the initial search, 41 studies were included in the review and informed the recommendations. No studies providing level one data were identified in this systematic review, all studies included were cohort or case-control studies.

CONCLUSIONS

There is a lack of level 1 data addressing the issue of surveillance of patients following partial pancreatectomy for non-invasive IPMN. The definition of remnant pancreatic lesion in this setting is largely heterogeneous across all studies evaluated. Herein we propose an inclusive definition of remnant pancreatic lesions to guide future prospective efforts for reporting the natural history and long-term outcomes of these patients.

Association Between Clinical Backgrounds and Malignant Progression of Suspected Intraductal Papillary Mucinous Neoplasm

OBJECTIVES

Some intraductal papillary mucinous neoplasms (IPMNs) have malignant potential and can become pancreatic cancer. The mechanism behind the malignant progression of IPMN remains unknown. We aimed to identify the risk factors and interactions between backgrounds for IPMN.

METHODS

We retrospectively enrolled 980 patients of pancreatic cancer or suspected IPMN (sIPMN) who underwent endoscopic ultrasound or retrograde cholangiopancreatography. We classified them into pancreatic cancer, high-risk sIPMN, and low-risk sIPMN, and investigated the risk factors for high-risk sIPMN.

RESULTS

Smoking habits (odds ratio [OR], 3.74; 95% confidence interval [CI], 2.04-6.85; P < 0.001), serum carbohydrate antigen 19-9 ≥37 U/mL (OR, 6.30; 95% CI, 2.88-13.80; P < 0.001), and family history of cancers (OR, 2.38; 95% CI, 1.30-4.37; P = 0.005) were independent risk factors for high-risk suspected IPMN. Odds ratios of diabetes and neutrophil-to-lymphocyte ratio of 2.45 or greater were significantly higher in patients with a family history of cancer than those without a family history of cancer (OR, 3.28; 95% CI, 0.52-20.80 vs 1.85; 95% CI, 0.78-4.41; OR, 2.44; 95% CI, 0.81-7.34 vs 1.24; 95% CI, 0.67-2.30, respectively).

CONCLUSIONS

Understanding the interactions between background factors can effectively prevent IPMNs' malignant transformation.