Simple Mucinous Cyst of the Pancreas: Review and Update

- According to the 2014 Baltimore Consensus Meeting, simple mucinous cysts are defined as macroscopic cysts that are greater than 1 cm in size with gastric-type flat mucinous lining and minimal cytologic atypia without ovarian-type stroma. This lesion has not been widely recognized and has undergone a recent nomenclature change owing to unclear pathogenesis and biologic behavior. Mucinous pancreatic cystic lesions are generally considered precursor lesions of pancreatic adenocarcinoma. However, simple mucinous cysts generally have benign behavior with no recurrence or malignant transformation during short follow-up periods.

- To provide a brief update and summary of the evolving nomenclature and current knowledge of simple mucinous cysts with an overview of their clinical, histopathologic, immunohistochemical, and molecular characteristics, as well as discussion of their differential diagnoses and biological behavior.

- Analysis of the pertinent literature (PubMed) and authors' clinical practice experience based on institutional and consultation materials.

- Simple mucinous cyst has undergone a nomenclature evolution from mucinous nonneoplastic cyst to the current recommended name of simple mucinous cyst to reflect its unclear pathogenesis and progression. The malignant potential of simple mucinous cyst is still debatable. Recent molecular studies support a neoplastic process, but these cysts generally exhibit benign behavior without recurrence or malignant transformation. Therefore, accurate diagnosis of simple mucinous cysts is critical to distinguish them from other more common and aggressive mucinous pancreatic cysts. Studies with larger cohorts and longer clinical follow-up data are needed to further determine the biologic behavior of this cyst and implications for prognosis.