Secondary Chondrosarcoma - DNB Ortho April 2023

Secondary Chondrosarcoma

a) Description and Likely Causes [3 Marks]

Definition: Secondary chondrosarcoma is a malignant cartilaginous tumor that arises from a pre-existing benign cartilaginous lesion. This contrasts with primary chondrosarcoma, which arises de novo.

Likely Causes / Precursor Lesions:

• Osteochondroma: The most common benign lesion that can undergo malignant transformation to secondary chondrosarcoma.
• Enchondroma: Especially multiple enchondromatosis conditions like Ollier's disease and Maffucci syndrome carry a risk of malignant transformation.
• Other Causes: Rarely from chondroblastoma or from a previously treated benign cartilaginous lesion.

b) Radiological Features, Histopathology & Management Principles [7 Marks]

Radiological Features [4 Marks]

• Location: Typically involves metaphyseal regions near growth plates, often the pelvis, femur, and scapula.
• Lesion Characteristics:
  • Presence of a cartilage cap > 2 cm thick in exostoses (osteochondroma) suggests malignant transformation.
  • Cortical destruction or irregularity.
  • Endosteal scalloping and expansion.
  • Calcifications within the mass (popcorn or ring-and-arc pattern) may be present but more irregular than benign lesions.
  • Soft tissue extension or mass may be seen.

Histopathological Features [3 Marks]

• Cellularity: Increased cellularity compared to benign precursor.
• Cell Type: Malignant chondrocytes with atypia, hyperchromatic nuclei, binucleation, and mitotic figures may be present.
• Matrix: Cartilaginous matrix with varying degrees of…