Pathophysiology
1) neoplasm that produces bone (both mineralized and unmineralized) 2) most common in long-bone metaphyses (proximal humerus and tibia and distal femur) 3) metastases are to lung and skeleton
Signs and Symptoms
1) pain and enlargement of affected area 2) fever
Characteristic Test Findings
Radiology – 1) Codman’s triangle (new bone formation at margin of soft tissue) 2) sunburst appearance (spiculations in reactive periosteal tissue) 3) mass lesion with moth-eaten appearance
Histology/Gross Pathology
1) hypervascular, spindle-cell neoplasm 2) main subtypes – fibroblastic, chondroblastic, osteoblastic 3) rarer subtypes – malignant fibrous histiocytosis, telangiectatic, small cell, and epitheliod
Associated Conditions
1) radiation therapy 2) Paget’s disease
Inheritance/Epidemiology
1) 70% occur at age 10-30 years 2) at ages 40-60 occurs as malignant transformation (of Paget’s disease, in radiated tissues) 3) male to female, 2:1
Treatment
preoperative chemotherapy (doxorubicin, ifosfamide, cisplatin), surgical resection (limb-sparing if possible), postoperative chemotherapy
Tips for USMLE
1) osteosarcomas are radiation resistant 2) if Codman’s triangle is mentioned, think osteosarcoma 3) if “sunburst” tumor is mentioned, think osteosarcoma
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