Osteosarcoma: Medical Term Breakdown and Clinical Overview

Osteosarcoma = osteo- (bone) + sarc- (flesh/connective tissue) + -oma (tumor) = malignant bone-forming mesenchymal tumor.

Epidemiology

• Most common primary bone sarcoma (excluding myeloma).
• Bimodal: adolescents (10–20 yr, growth spurt) & >60 yr (Paget's, radiation-induced).
• Male predominance (1.5:1).
• Sites: Distal femur, proximal tibia, proximal humerus (metaphyses of long bones).

Pathology

• Malignant osteoid production by pleomorphic stromal cells.
• Subtypes: Osteoblastic, Chondroblastic, Fibroblastic, Telangiectatic, Small cell, Surface (parosteal, periosteal).

Presentation

• Pain (worse at night, activity-related)
• Swelling, palpable mass
• Pathologic fracture (10–15%)
• Limited joint motion

Workup & Staging

1. Plain radiographs (sunburst periosteal reaction, Codman's triangle)
2. MRI (local extent, skip metastases)
3. Chest CT (lung mets – most common)
4. Bone scan / PET-CT
5. Biopsy (core needle) – confirms diagnosis, subtype

Treatment (Multimodal)

• Neoadjuvant Chemotherapy: MAP (Methotrexate, Doxorubicin, Cisplatin) ± Ifosfamide.
• Wide Surgical Resection: Limb-salvage (endoprosthesis, allograft, rotationplasty) >90%; amputation if neurovascular involvement.
• Adjuvant Chemotherapy: Based on histologic necrosis response (>90% necrosis = good prognosis).

Prognosis

Localized, good necrosis: 5-yr OS 70–75%. Metastatic: 20–30%. Recurrence: lung > bone.