Introduction
- Usually affects young adults
- Mean age at diagnosis is 28 years
- Variable duration of symptoms prior to diagnosis
- Prognosis better than with conventional osteosarcoma
Location
Majority of tumors located in long bones, principally in metaphyseal region, less commonly in diaphysis
Plain films
Size
Usually large
Tumor effect on bone
Lytic lesion with internal trabeculations and variable degrees of internal sclerosis
Bone response to tumor
Generally poorly defined with wide zone of transition; may demonstrate sharp, well-demarcated margins, however
Cortex
Lesions generally contained within bone without soft tissue extension or periosteal reaction
Pathology
- Microscopic: Lesions may be difficult to differentiate from fibrous dysplasia
- Well-formed trabeculae in variably cellular fibrous stroma
- Cytological atypia usually minimal
- Absence of osteoblasts and osteoclasts rimming trabeculae and infiltration between pre-existing bone trabeculae supports malignant diagnosis
Differential diagnosis
- Fibrous dysplasia
- Fibrosarcoma
- Infection
- Lymphoma
Complications
Pathologic fracture (rare)
