Well differentiated intramedullary osteosarcoma

Topic Completed: 1 August 2013

Revised: 28 December 2018

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Well differentiated intramedullary osteosarcoma

Nat Pernick, M.D.
Page views in 2018: 984
Page views in 2019 to date: 964
Cite this page: Pernick N Well differentiated intramedullary osteosarcoma. website. Accessed November 19th, 2019.
Definition / general
  • Very rare; also called low grade osteosarcoma, intraosseous osteosarcoma
  • Usually adults, femur and tibia
  • Excellent prognosis, but 15% eventually develop conventional (high grade) osteosarcoma
Radiology description
  • Large lesions with cortical destruction and extraosseous extension
  • Much of tumor is well circumscribed, with a focally aggressive growth pattern
Radiology images

Distal femoral metaphysis

Part of cortex destroyed

Metaphysis and epiphysis of tibia

Gross description
  • Firm, fibrous, no fish - flesh appearance
Gross images

Proximal portion of humerus

Medullary cavity

Microscopic (histologic) description
  • So bland that appears benign but invades bone and soft tissue
  • Hypocellular spindle cells with mild atypia, marked collagen production
  • Variable osteoid production
  • No/rare mitotic figures
Microscopic (histologic) images

Markedly pleomorphic osteoblasts

Focal osteoid formation

Neoplastic osteoblasts

Heavily calcified osteoid

Conventional intramedullary osteosarcoma

Low grade cartilaginous differentiation

"Herringbone" pattern

Spindled, fibroblast-like tumor cells

Minimal osteoid deposition

Dense osteoid surrounds blood vessel

Treated conventional osteosarcoma

Amorphous deposits of osteoid in stroma

Mature - appearing bone

Broad trabeculae of bone

Molecular / cytogenetics description
  • Usually diploid
Differential diagnosis
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