Clinicopathological Features and Prognosis of Mucinous Cystic Neoplasm With Ovarian-Type Stroma A Multi-Institutional Study of the Japan Pancreas Society

Objective: The aim of this study was to elucidate the clinicopathological features and prognosis of mucinous cystic neoplasms (MCNs). Materials and Methods: We performed a multi-institutional, retrospective study on a collected series of patients with MCN pathologically defined by ovarian-type stroma. Clinicopathological features and prognosis were investigated. Result: Mucinous cystic neoplasm was confirmed in 156 cases, including 129 adenomas (82.7%) and 21 noninvasive (13.4%) and 6 invasive carcinomas (3.9%). Patients with MCN were exclusively women (98.1%) with the mean age of 48.1 years. All but 1 MCN were in the pancreatic body/tail region with a mean size of 65.3 mm. Communication between the cyst and the pancreatic duct was found in 18.1%. The 3-, 5-, and 10-year survival rates were 97.6%, 96.6%, and 96.6%, respectively. A significant difference in the survival rates was observed between adenomas and carcinomas and between minimally invasive carcinomas and invasive carcinomas. Cyst diameter and presence of mural nodule were predictive of malignant MCN. Conclusions: Mucinous cystic neoplasm is a rare but distinctive pancreatic cystic neoplasm with a favorable overall prognosis. All MCNs should be resected to prevent malignant changes but can be observed an appropriate time when the lesion is small without the presence of mural nodules.