Differential diagnosis (children/adolescents <18Y)

• Patellofemoral pain (usually adolescents)

• Osgood-Schlatter's disease / Sinding–Larsen Johansson syndrome

• Referred pain from hip (e.g. slipped capital femoral epiphysis)

• Hypermobility syndrome; growing pains; patellar subluxation/instability

• Osteochondritis dissecans

• Osteomyelitis and septic arthitis

• Tumours

• Patellar tendonitis

• Discoid lateral meniscus)

Question

A 15-year-old boy presents with a two-month-history of fever, fatigue and a painful, red swelling just above his left knee. This pain is usually worse at night. There is no history of trauma.

Which is the SINGLE MOST likely diagnosis in this patient?

1. Osgood–Schlatter’s disease

2. Reactive arthritis

3. Osteomyelitis

4. Juvenile idiopathic arthritis

5. Ewing’s sarcoma

Ewing’s sarcoma is a rare but important diagnosis not to miss. It accounts for 2% of all childhood cancers. It is more common in males and typically presents in children and young adults aged 5–20 years old. It may mimic an infective process, but red flag symptoms of fever, persistent pain (including nocturnal and rest pain) and persistent localised swelling should prompt an urgent referral to exclude a malignant lesion.

Resource

• Suspected Cancer: recognition and referral. NG12. 2015 (updated 2021)