Table of Contents
Definition / general | Radiology description | Treatment | Radiology images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Differential diagnosis | Additional referencesCite this page: Stockman DL. Dedifferentiated chondrosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bonedediffchondrosarcoma.html. Accessed March 9th, 2021.
Definition / general
- High grade malignant neoplasm composed of a well differentiated cartilaginous tumor, usually low grade conventional chondrosarcoma, with either high grade pleomorphic, undifferentiated pleomorphic (UPS) or spindle cell sarcoma like areas
- Less frequently originates as an enchondroma or osteochondroma, in patients with hereditary exostosis
- Bimodal age distribution; patients with exostosis may develop chondrosarcomas earlier in life
- Poor prognosis, with 5 year survival of 10% to 35% (pelvis)
Radiology description
- Low grade component manifests as mineralized area with rings and arcs
- High grade component is lytic and aggressive, with permeation and destruction of underlying bone
Treatment
- Wide excision and systemic therapy, although the latter seems to be relatively ineffective
- Many patients are older and have medical conditions limiting tolerance to therapy
Gross description
- Cartilage tumor adjacent to fish-flesh appearance of sarcoma
Microscopic (histologic) description
- Conventional chondrosarcoma juxtaposed to high grade pleomorphic or spindle cell sarcoma
- May have features of angiosarcoma, clear cell chondrosarcoma, fibrosarcoma, osteosarcoma, rhabdomyosarcoma, squamous cell carcinoma
Microscopic (histologic) images
Positive stains
Differential diagnosis
- Chondroblastic osteosarcoma: young patients; gradual transition from high grade cartilaginous tumor to spindle cell sarcoma
- High grade spindle cell sarcoma / undifferentiated pleomorphic sarcoma of bone
- Metastatic sarcomatoid carcinoma
Additional references