title: Osteoclast-like giant cell tumor of the pancreas associated with mucus-secreting adenocarcinoma. Case report and discussion of the histogenesis.
abstract: OBJECTIVE
  The osteoclast-like giant cell tumor of the pancreas is a rare entity that closely resembles giant cell tumor of the bone, which has also been observed in many other organs. Some tumors also contain areas of ductal adenocarcinoma. Conflicting opinions exist regarding the tumor origin, whether it is mesenchymal or epithelial, neoplastic or reactive.
  
  
  METHODS
  We report the case of a 69-year-old Brazilian man with a mass in the head of the pancreas, the histological examination of which revealed a predominant component of osteoclast-like giant cells within a background of pleomorphic mononuclear cells with osteoid formation and other areas composed of conventional mucus-secreting adenocarcinoma.
  
  
  RESULTS
  Immunohistochemistry showed that carcinoma cells of the usual type expressed epithelial antigens (EMA and cytokeratin) and lysozyme; the giant cells expressed vimentin, CD45, CD68, and lysozyme; and the mononuclear cells expressed macrophage marker (HAM56), vimentin, and lysozyme, and only some of them expressed epithelial markers, CD45, and CD68.
  
  
  CONCLUSIONS
  Our immunohistochemical findings reveal that the giant cells in this case are of mesenchymal origin may be from the bone marrow cells. We believe that it is important to determine the histogenesis in each case to carry out the pertinent adjuvant therapy.
authors.affiliation: Department of Pathology, College of Medicine, Universidade do Oeste Paulista, Presidente Prudente, São Paulo, Brazil. gica@muranet.com.br
authors.forename: Gisele A
authors.initials: GA
authors.lastname: Nai
authors.forename: Enio
authors.initials: E
authors.lastname: Amico
authors.forename: Vanderlei R
authors.initials: VR
authors.lastname: Gimenez
authors.forename: Marcello
authors.initials: M
authors.lastname: Guilmar
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000368:Aged; D017809:Fatal Outcome; D005870:Giant Cell Tumors / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D009093:Mucus / Q000378:metabolism; D010010:Osteoclasts / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D014057:Tomography, X-Ray Computed