title: Well-differentiated mesenteric liposarcoma with osseous metaplasia: a potential diagnostic dilemma for the pathologist.
abstract: BACKGROUND
  Mesenteric liposarcoma is a rare intra-abdominal sarcoma with very few cases reported in the available English literature. Incomplete resection of the tumor leads to recurrence, and recurrent tumors carry a risk of dedifferentiation. Dedifferentiation in liposarcoma manifests as a nonlipogenic sarcoma, which is usually high-grade and may show osteosarcomatous differentiation rarely. To the best of our knowledge, osteoid metaplasia in a well-differentiated liposarcoma without evidence of dedifferentiation has not been documented in the available literature.
  
  
  METHODS
  We describe the case of a middle-aged adult man with a well-differentiated liposarcoma of the mesentery. The patient presented with a recurrent tumor 5 years after the initial surgery. At recurrence, the histological features were those of a well-differentiated liposarcoma with focal osseous metaplasia without any evidence of dedifferentiation in the extensive sections examined.
  
  
  CONCLUSIONS
  Osseous metaplasia is a rare phenomenon in lipomas and dedifferentiated liposarcomas. Such an occurrence in a recurrent well-differentiated liposarcoma is a perplexing problem due to the potential confusion with dedifferentiation. This needs to be recognized to avoid overzealous chemotherapy and/or radiotherapy, which is required for dedifferentiated tumors.
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India. ruchika257@yahoo.com
authors.forename: Ruchika
authors.initials: R
authors.lastname: Gupta
authors.forename: Alok
authors.initials: A
authors.lastname: Sharma
authors.forename: Raman
authors.initials: R
authors.lastname: Arora
authors.forename: Mukund P
authors.initials: MP
authors.lastname: Kulkarni
authors.forename: T K
authors.initials: TK
authors.lastname: Chattopadhaya
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Singh
mesh_terms: D002114:Calcinosis / Q000473:pathology*; D003937:Diagnosis, Differential; D006801:Humans; D008080:Liposarcoma / Q000473:pathology* / Q000601:surgery; D008297:Male; D008643:Mesentery / Q000473:pathology* / Q000601:surgery; D008679:Metaplasia; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000601:surgery; D010534:Peritoneal Neoplasms / Q000473:pathology* / Q000601:surgery