title: A large parosteal ossifying lipoma of lower limb encircling the femur.
abstract: BACKGROUND
  Lipoma is a benign soft tissue neoplasm that may contain mesenchymal elements, as a result of metaplastic process. Ossification in benign and malignant soft tissue tumors can also manifest due to metaplastic process.
  
  
  METHODS
  A 45 year old woman presented with a large thigh mass. The mass was developed one and a half year ago which insidiously increased in size and was associated with movement restriction. Radiological findings revealed soft tissue neoplasm on antero-medial aspect of thigh encircling the femur and displacing adjacent muscles. Fine trabeculations were seen in neoplasm suggestive of ossification. Excision of the mass was performed and histopathology revealed adipocytes with mature bony trabeculae possessing prominent osteoblastic rimming suggestive of ossifying lipoma.
  
  
  CONCLUSIONS
  It is important to recognize this variant of lipoma as it is associated with a better clinical outcome in contrast to most of the deep seated soft tissue neoplasms. Secondly it should also be differentiated from myositis ossificans and heterologous differentiation in other soft tissue neoplasms. We suggest an algorithmic approach to the diagnosis of ossifying soft tissue neoplasms histopathologically. Mature bony trabeculae with prominent osteoblastic rimming in a soft tissue lesion are due to a metaplastic process and should not be confused with osteosarcoma.
authors.forename: Atif Ali
authors.initials: AA
authors.lastname: Hashmi
authors.forename: Babar
authors.initials: B
authors.lastname: Malik
authors.forename: Muhammad Muzzammil
authors.initials: MM
authors.lastname: Edhi
authors.forename: Naveen
authors.initials: N
authors.lastname: Faridi
authors.affiliation: Dhaka medical college, Dhaka, Bangladesh. ashrafulmuhammad@gmail.com.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ashraful