Ruptured mucinous cystic neoplasm with an associated invasive carcinoma of pancreatic head in a pregnant woman: report of a case and review of literature.

Mucinous cystic neoplasm (MCN) of the pancreas is characterized by mucin-producing columnar epithelium and an ovarian-type stroma. It occurs almost exclusively in women and is almost always located in the pancreatic body or tail. Here, we report a case of large MCN located in the pancreatic head but not in the body nor tail in a 32-year-old pregnant woman, which was thought to have grown rapidly during pregnancy. It was ruptured at 34 weeks of gestation and the patient was admitted to the emergency department of the University of Fukui Hospital with an acute abdomen. Emergency cesarean section followed by pancreaticoduodenectomy was performed. The tumor consisted of many small cysts lined by a single-layer of mucinous epithelium with papillary growth and partial solid parts showing invasive growth and sarcomatoid changes, indicating mucinous cystic neoplasm with an associated invasive carcinoma (previously referred as mucinous cystadenocarcinoma). Thickened septa revealed ovarian-type stroma strongly positive for α-inhibin and partly positive for progesterone receptor immunohistochemically. We also review and discuss previous reports of MCNs including those with an associated invasive carcinoma in pregnant patients.