Snapshot An 11-year-old male was referred for pain and swelling of the right proximal tibia. The pain wakes him up at night and he wakes up with cold sweats. He recently participated in a sporting event which led to exacerbation of the pain. On examination, he walks with an antalgic gait. The range of knee motion was 10 to 80 degrees and limited by pain. The proximal leg was warm and tender to palpation. Distal pulses were normal. X-rays revealed a permeative, mixed sclerotic-lyic lesion in the proximal tibial metaphysis. CT chest revealed a small 8mm nodule in the right upper lobe suspicious for metastatic disease. Core biopsy revealed high-grade osteosarcoma. Introduction Osteosarcoma is the most common primary sarcoma of bone most common malignancy of bone is metastatic disease most common primary malignancy of bone is myeloma Epidemiology males bimodal age distribution 10-14 years elderly patients, often associated with Paget's disease Location metaphysis most common site is the distal femur and proximal tibia (around the knee) Metastasis lung is most common site of metastasis, followed by bone Genetics carriers of Retinoblastoma tumor suppressor gene (Rb) are predisposed to osteosarcoma Symptoms Symptoms progressive, intractable pain, worse at night swelling constitutional symptoms (fever, weight loss, night sweats) may be absent may be mistaken for growing pains Physical exam erythema and enlargement Evaluation Elevated alkaline phosphatase may be 2-3 times normal value Imaging Radiographs blastic and destructive lesion sun-burst or hair on end pattern of matrix mineralization periosteal new bone formation (Codman's triangle) large soft tissue mass with maintenance of bone cortices MRI of the entire involved bone soft tissue involvement neurovascular involvement skip metastases (within the same bone) Bone scan very hot also to detect bone metastases CT of the chest to evaluate for lung metastases Histology Histology tumor cells show significant atypia, and produce "lacey" osteoid stroma cells show malignant characteristics with atypia, high nuclear to cytoplasmic ratio, and abnormal mitotic figures Treatment Diagnosis biopsy is required for tissue diagnosis Operative pre- and post-op chemotherapy and limb sparing surgery multi-agent chemotherapy (e.g. methotrexate, doxorubicin, cisplatin, ifosfamide) preoperative chemotherapy for 8-12 weeks followed by maintenance chemotherapy for 6-12 months after surgical resection amputation may be necessary Prognosis 76% long-term survival with modern treatment poor prognostic factors include advanced stage (most predictive of survival) response to chemotherapy (percentage of tumor necrosis) tumor site and size high serum alkaline phosphatase and lactate dehydrogenase surgical margins Differentials & Groups Destructive bone lesion in young patients (1) Treatment is Wide Resection & Chemotherapy (2) Osteosarcoma (intramed. & periosteal) • • Ewing's sarcoma • • Leukemia • Lymphoma • Eosinophilic granuloma • Osteomyelitis • Desmoplastic fibroma • MFH / fibrosarcoma • Dedifferentiated chondrosarcoma • Secondary sarcoma • Rhabdomyosarcoma (soft tissue) • ASSUMPTIONS: (1) Younger patient is < 40 yrs; (2) assuming no impending fracture IBank Location Age Xray Xray CT Bone scan MRI Histo Case A Proximal tibia 13 Case A Prox. tibia 14 Case B Distal femur 17 Case C Distal femur 11 Case D Pelvis 15 Case E Femoral shaft 21 Case F Prox. humerus 14 Case F Ankle 12