title: An unusual case of undifferentiated carcinoma in situ with osteoclast-like giant cells of the pancreas.
abstract: OBJECTIVE
  We report an unusual case of undifferentiated carcinoma in situ with osteoclast-like giant cells (UC with OGCs) in a 68-year-old Japanese woman.
  
  
  METHODS
  Preoperative examinations revealed an unidentifiable mass lesion within the main pancreatic duct (MPD) in the pancreatic head, accompanied by a dilated MPD distal to the mass lesion, which was suspected to be an intraductal papillary-mucinous neoplasm of the main-duct type with acute pancreatitis because of an increased serum amylase level. A pancreaticoduodenectomy was performed.
  
  
  RESULTS
  A pencil-like tumor occupied the lumen of the MPD of the pancreatic head without a visible pancreatic parenchymal mass. The intraductal tumor included a sheet of spindle cells intermingled with scattered OGCs and pleomorphic giant cells. A poorly developed glandular pattern was occasionally observed at the tumor periphery. These findings were consistent with conventional UC with OGCs. However, extraductal invasion was not found in an extensive histopathologic examination, although focal intraductal spreading into the epithelium of the first branch of the MPD was observed.
  
  
  CONCLUSIONS
  Undifferentiated carcinoma with OGCs usually exhibits an invasive tumor at diagnosis and is associated with a poor outcome, but the patient is alive without recurrence 22 months after surgery. To our knowledge, this is the first reported case of UC in situ without evident extraductal invasion in English literature.
authors.affiliation: Division of Surgery, Yamagata Prefectural Shinjo Hospital, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tezuka
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Yamakawa
authors.forename: Akira
authors.initials: A
authors.lastname: Jingu
authors.forename: Yushi
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Wataru
authors.initials: W
authors.lastname: Kimura
mesh_terms: D000368:Aged; D002278:Carcinoma in Situ / Q000473:pathology* / Q000601:surgery; D002454:Cell Differentiation; D005260:Female; D006801:Humans; D010010:Osteoclasts / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000473:pathology* / Q000601:surgery; D016577:Pancreaticoduodenectomy; D016896:Treatment Outcome