Malignant potential of intraductal papillary mucinous neoplasm (IPMN) of the pancreas: imaging assessment of IPMN-derived cancer and concomitant pancreatic ductal adenocarcinoma

Vollständiger Abstract

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Abstract The detection of pancreatic cystic lesions (PCLs) has increased markedly with the widespread use of cross-sectional imaging. Although the true proportion of intraductal papillary mucinous neoplasms (IPMNs) among PCLs remains uncertain, IPMN is considered to account for most PCLs and is a representative precursor lesion of pancreatic ductal adenocarcinoma (PDAC). However, not all PCLs should be assumed to represent IPMN, because this assumption may lead to unnecessary surveillance or overtreatment. Therefore, radiologists should first determine whether a PCL truly represents IPMN, particularly by differentiating it from lesions without malignant potential, such as serous cystic neoplasm. Once IPMN is diagnosed, appropriate risk stratification is required to identify IPMN-derived cancer, defined in this review as IPMN with high-grade dysplasia or associated invasive carcinoma. High-risk stigmata and worrisome features proposed in current guidelines are central to this assessment. However, the risk associated with each factor is not uniform; therefore, risk assessment and management decisions should consider both the number of risk factors present and the relative weight of each factor. Concomitant PDAC may also arise separately from the PCL, possibly reflecting a field defect of the entire pancreas. Unlike IPMN-derived cancer, concomitant PDAC may develop independently of cyst size or growth and is often detected at an advanced stage. Therefore, surveillance of patients with IPMN should include not only evaluation of the PCL itself and assessment for IPMN-derived cancer, but also systematic assessment of the entire pancreas for concomitant PDAC. This review discusses the differential diagnosis of PCLs, imaging assessment of IPMN-derived cancer, the concept and imaging clues of concomitant PDAC, and practical considerations for surveillance strategies.