Tumor biology

Rare, aggressive, malignant tumor

Gender

M:F = 2:1

Radiographic appearance

Confusing radiographic picture, with aggressive and nonaggressive features possible
Generally a cystic/lytic lesion, although indistinct margins may be seen

Site

Principally involves femur, tibia, and humerus at metaphyseal level

Tumor effect on bone

Most common pattern is lytic and expansile; may have a moth-eaten or permeative pattern (rare)

Periosteal reaction

May or may not be present

Soft tissue mass

Generally present, with hemorrhagic tumor extending into soft tissues

Differential diagnosis

Similar for all lytic expansile metaphyseal lesions

  • Aneurysmal bone cyst
  • Giant cell tumor
  • Brown tumor
  • Osteoblastoma

Pathology

Characterized by cystic, blood-filled channels lined by malignant tumor cells

Treatment

  • Similar to conventional osteosarcoma
  • Lesion responsive to chemotherapy
    • Previous reports of particularly bad prognosis for this variant of osteosarcoma probably innaccurate