- See: Classic osteosarcoma
- Discussion:
- uncommon variant of classic osteosarcoma;
- primarily affects young adults;
- presents as an enlarging, painless mass growing on surface of the bone;
- most frequently seen in anterior proximal tibia & the posterior surface of the distal femur;
- Diagnostic studies:
- large external, poorly mineralized mass w/ in a depression of cortical erosion;
- w/ irregular margins & periosteal reaction;
- sunburst appearance is composed of malignant cartilage and bone;
- look for spiculed radiating mineralization;
- diff dx:
- classic osteosarcoma
- periosteal chondroma
- juxtacortical chondrosarcoma
- periosteal desmoid lesion:
- a tumor simulator;
- look for bone irregularity along the posteromedial aspect of the distal femur at the insertion of the adductor magnus or the origin of gastroc muscle;
- most commonly occurs in patients who are age 10 to 15 years;
- are not symptomatic (no mass, pain, or swelling);
- ref: Developmental defects of the distal femoral metaphysis.
- Bone Scans:
- bone scans show a disproportionate uptake throughout tumor, considering its predominantly radiolucent appearance;
- CT Scan:
- CT depicts tumor lying in shallow cortical defect w/ moderate calcification;
- Histology:
- regions of malignant mesenchymal stroma, areas of neoplastic osteoid scattered in & about lobules of low grade mature cartilage;
- chondroid matrix may predominate in periosteal chondroma;
- periosteal lesion will have areas of chondroid differentiation in addition to osteoid matrix;
- normall appearing trabeculae are absent;
- chondroblastic differentiation is seen, which by itself might indicate periosteal chondrosarcoma;
- dx of periosteal osteosarcoma is clinched by combination of cartilage, malignant bone, osteoid and fibrosarcomatous tisse;
- Treatment and Prognosis:
- prognosis for patients with periosteal osteosarcoma is fair.
- extension through cortex occurs earlier than in parosteal osteosarcoma;
- bony extension implies worse prognosis w/ higher incidence of pulmonary metastases;
- lesion is almost always amenable to excision with a wide margin.
- chemotherapy is indicated only for higher grade, dedifferentiated tumors;
Osteosarcomas arising on the surfaces of long bones.
Periosteal Osteosarcoma: long-term Outcome and Risk of Late Recurrence.