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Chondrosarcoma

Summary

  • Malignant cartilaginous tumour arising from bone or soft tissue
  • Characterised by production of cartilage matrix
  • Imaging shows lobulated, lytic lesion with ring and arc calcifications1

Pathophysiology

  • Arises from cartilage-forming cells or mesenchymal stem cells
  • Classified into three grades based on cellularity, nuclear atypia, and mitotic activity
  • Subtypes include conventional, clear cell, dedifferentiated, and mesenchymal chondrosarcoma

Demographics

  • Second most common primary bone tumour after osteosarcoma
  • Peak incidence in 5th to 7th decades of life
  • Slight male predominance (1.5:1)
  • Most common sites: pelvis, proximal femur, proximal humerus, and ribs

Diagnosis

  • Clinical presentation:
    • Pain and swelling at the affected site
    • Pathological fracture in advanced cases
  • Histopathology:
    • Lobulated architecture with hyaline cartilage matrix
    • Varying degrees of cellularity and nuclear atypia

  • Molecular markers:

    • IDH½ mutations in conventional and dedifferentiated subtypes

  • At the skull base, chondrosarcoma characteristically arises off-midline from the petro-occipital (petroclival) synchondrosis — a key distinction from midline chordoma

Imaging

  • CT: lytic, destructive lesion with chondroid ring-and-arc or "popcorn" calcification
  • MRI:
    • T1 low-intermediate; very high T2 signal (hyaline cartilage) with a lobulated appearance
    • Heterogeneous, often peripheral/septal enhancement

panels-1

  • A 50-year-old patient presented with diplopia.
  • Imaging showed a large enhancing non-calcified lesion centred on the left petrous apex with invasion of the cavernous sinus.

Treatment

  • Wide surgical resection, usually with adjuvant proton/photon radiotherapy; conventional chemotherapy is of little benefit

Differential diagnosis (skull base)

Imaging differential Differentiating feature
Chordoma Midline (clival) rather than off-midline; T2-bright but usually less than chondrosarcoma; brachyury-positive
Skull base metastasis / plasmacytoma Destructive marrow-replacing lesion without chondroid matrix
Chondroid meningioma Dural-based with a dural tail and avid enhancement
Fibrous dysplasia Expansile ground-glass matrix without lytic destruction

  1. Flemming et al. Enchondroma and chondrosarcoma. 2000. Seminars in musculoskeletal radiology - Open in new tab. ↩