Tumor biology

  • Rare, slow-growing, benign, generally active cartilage lesion
  • Not known to metastasize
  • Arises on the surface of bone with underlying cortical scalloping

Age

Second through fourth decades

Gender

M:F = 1:1

Presentation

  • Pain, tenderness at site of lesion
  • Often accompanied by swelling

Physical findings

Localized swelling may be present

Plain films

Site
  • Lesion eccentric, subperiosteal in location, external to cortex
  • Medullary canal not involved
  • Most common site: metaphyseal cortex of long bones (especially proximal humerus and femur), small tubular bones of hands and feet
Size

Variable


Tumor effect on bone
  • Periosteal-based soft tissue lesion
  • Typically causes erosion/scalloping.
Bone response to tumor
  • Lesion is well defined, shallow, geographic
  • Sharp sclerotic interface with underlying eroded cortical margin
  • Peripheral periosteal elevation and reaction may be seen


Matrix
  • Scattered calcifications may be present
  • Lesions may be highly calcified and radiopaque


Cortex

Cortical scalloping/erosion by the overlying juxtacortical mass


Soft tissue mass

Always present


Differential diagnosis

  • Periosteal chondrosarcoma
  • Periosteal osteosarcoma
  • Soft tissue neoplasm eroding adjacent cortical bone


Pathology

  • Gross: Cartilage nodules located on surface of cortex
  • Microscopic: Hyaline cartilage showing variable cellularity
  • Cytological atypia may be present; correlation with radiologic appearance critical
  • New bone formation may be present at interface of lesion and underlying cortical bone


Diagnosis and treatment

  • Treatment of choice: en bloc resection with an intact narrow rim of normal bone
  • Curettage has relatively high risk of recurrence
  • Spilling cartilage into soft tissues by curettage increases risk of local relapse