oncology
Osteosarcoma
advanced
6 min
28 marks
6 questions
Clinical Scenario
A 16-year-old male presents with a 3-month history of progressively worsening left knee pain. The pain is worse at night and not relieved by rest or NSAIDs. He has noticed swelling around the knee. There is no history of trauma. On examination, there is a firm, non-tender mass in the distal thigh with restricted knee movement. Laboratory tests show elevated ALP and LDH. X-ray shows an aggressive bone lesion.
AP and lateral radiographs of the left knee in a 16-year-old showing features of osteosarcoma of the distal femur. There is an aggressive metaphyseal lesion with mixed lytic and sclerotic pattern, sunburst periosteal reaction, Codman triangle (lifted periosteum), and a large soft tissue mass. The lesion extends towards but does not cross the physis. MRI and CT staging are required.
Image source: Open Access medical literature (NIH/PubMed Central) • CC-BY License
Questions
Question 1 (4 marks)
Describe the clinical features and radiographic appearances of osteosarcoma.
Question 2 (5 marks)
What is the staging workup for suspected osteosarcoma?
Question 3 (6 marks)
Describe the treatment principles including chemotherapy and surgery.
Question 4 (5 marks)
What are the surgical options for limb salvage?
Question 5 (4 marks)
Discuss prognostic factors and survival outcomes.
Question 6 (4 marks)
What are the variants of osteosarcoma and their significance?
Exam Day Cheat Sheet
Must Mention
- •Peak age 10-20, distal femur most common
- •Sunburst periosteal reaction + Codman triangle
- •MRI whole bone (skip lesions)
- •CT chest (lung mets 15-20%)
- •MAP: Methotrexate, Adriamycin, cisPlatin
- •>90% tumor necrosis = good prognosis
Common Pitfalls
- •Wrong biopsy technique
- •Missing skip lesion
- •Not knowing chemo drugs
- •Wrong necrosis threshold
- •Missing variants
- •Wrong survival rates