Ossification in pancreatic neoplasms: A report of three cases of neuroendocrine tumor, mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm with review of the literature

Heterotopic ossification (HO) is the formation of mature bone tissues in non-skeletal tissues and has been reported in various types of neoplasms. The presence of HO in pancreatic tumors is rare, with only 16 cases reported in the English literature, and the mechanism of HO formation remains unclear. In the present study, the 17th to 19th cases of HO in pancreatic neoplasms were described and the literature on HO in pancreatic neoplasms was reviewed. Three Japanese women with pancreatic masses on imaging underwent laparoscopic distal pancreatectomy. The three pancreatic masses were histopathologically diagnosed as a pancreatic neuroendocrine tumor (NET), mucinous cystic neoplasm (MCN), and intraductal papillary mucinous neoplasm, and HO was found in all of them. Neither pancreatic NET with HO nor MCN with HO has yet been reported in the English-language literature, and to our knowledge, these are the first such reports. Although rare, the knowledge that various types of pancreatic tumors, including NETs and MCNs, are associated with HO may be useful in daily practice, and the significance of tumor-associated HO is discussed.